Are iPad apps much more expensive to build than iPhone ones? Is there much less impetus to build an app for a platform that already provides a good browsing experience?
Facebook for iPhone was originally written by a non-facebook employee from what I understand who's now left the iOS development environment over philosophical differences with the app approval process. While facebook publishes their own app now, again, they weren't exactly the first to hit the platform in the first place.
What exactly are you expecting skype to do differently on the iPad than the iPhone? What are you expecting the non-iPhone shaped UI to give you that the iPhone shaped UI doesn't? The iPad isn't exactly a perfect platform for videoconferencing (no camera), and the phone version works fine.
All that said, lets talk about technical/policy/business issues which cause people to not specialize on the iPad.
First off: Business reasons.
Business wise, the iPad has very few users compared to the iPhone/iPod Touch formfactor. So when you write to that audience, you're paying for a generally more expensive app, to reach fewer people. Is this a bad thing? For companies that could grow too fast, it might be a positive thing, but on the whole a smaller audience is bad. On the plus side however, those who own iPads tend to be more affluent and are willing to buy more expensive applications, so you can get higher unit prices to somewhat compensate for that, if your concept is appealing to people.
Next up: Policy Issues
Apple is not the easiest of companies to "write software for". And while you're not writing it "for" them per se, you have to jump through a series of hoops they tell you to. And with the iPad, you have a list of guidelines to follow which are quite a bit different than with the iPhone/iPodTouch sized apps. Your apps need to handle all orientations for the most part, your apps need to observe the more complex menu-ing paradigms, your apps need to usually have more sophisticated art assets, and you also have a higher expectation of not looking "cruddy" for lack of a better word.
While the enforcement of these "guidelines" are all over the map, people routinely DO get rejected for violating some or all of them. This means the cost of iPad development goes up.
Technical considerations:
Hybrid apps, those which work both on the phone and pad in the "native" resolution of the platforms require you to either A> violate the assumptions of one or both platforms or B> create completely different screen layouts for each "mode" of the application. Those "modes" would be iPhone, iPad landscape, iPad Portrait. Menuing is different in the two orientations on the iPad, and expectations of pretty animations are much higher in general.
Until November or so, you'll see that additionally that iPad is on 3.2.1 of iOS and iPhones are on 4.0.1. This means the iPad is missing many of the cutting edge features that 4.x has. So if you're writing a hybrid app, you have to work around sometimes having certain features, and sometimes not, and additionally you have all the issue with different aspect ratios, etc.
Hopefully I've explained some of the issues. I've tried to be brief, this is a complicated subject, but basically, this is it, and it's also a huge barrier to entry, which means many good business opportunities still exist on the iPad.
It seems to me Android got this particular aspect a bit more right. I guess we'll see as those tablets start to come out, although Google bloggers are making it sound like most apps "just work.
So since the app uses graphics which are at the DPI of a 3G iphone (resolution 480x320), then you scale that up to 960x640 without redoing the art, you're going to get nasty jaggies, etc, as you just divided your DPI by 4.
Pretty much everything looks that pixelated when you magnify it 2x. I mean, open up your computer's screen magnification app and set it to 200x zoom, and see how bad everything looks.
It's somewhat similar to what standard def television looks like when blown up on a huge television screen which you then sit too close to, especially on PAL TVs (which aren't interlaced)
For many apps, I prefer to use them at 1x in the middle of the screen, especially ones I do not have to type on.
I don't know what the proper solution would be as I don't know how visual layout if handled in iOS development. There may have been no automated method for handling it other than simple image scaling. If that is the case, I would have expected Apple to push supporting higher resolution screens a lot sooner than they did.
The real factor here is the iPad has only been on the market for 5 months. We've had the iPhone SDK for over 2 years now. We just need more time to figure things out.
to your point: what do we expect skype to do differently on iPad vs iPhone? how about something creative?
it's embarrassing that Facebook doesn't have an iPad app by now. Kudos to Twitter for trying (and shipping) something new and exciting.
it's set up for much more noodling/discovery of tweets and people, rather than just looking over a timeline.
I honestly do not care if I'm doing iPad or iPhone or iPhone 4 development, all pay well enough and all have interesting challenges. I don't think the iPad is a magic producing device of infinite wonder, but the thing is pretty neat and for certain projects (processing power or display space based ones) it can actually be a less expensive platform to develop for.
However, people are not willing to shoulder the extra costs from the differences I covered in my post, so do not make as many iPad apps, as they can make a fantastic iPhone app for the same price as an okay iPad app or somewhat featureless hybrid app .
It is a more rigorous approval standard for a smaller market. Why is that so hard to fathom it would have fewer people participating in it?
As for Facebook, what is an app going to bring the website doesn't? You can't take pictures on the device, so that's out (and one of the main points of the iPhone app). You can do pretty much everything else via the website. It works just fine from the iPad web browser.
The app approval process is fairly terrifying, and I'd buy that it might be a reason higher-overhead projects on the iPad aren't being built.. That's the sort of aspect I was interested in getting folks' opinions on.
The other category of apps that don't make sense on the iPad are the "small utility that you always want to have in your pocket" apps. The iPad isn't small, and you don't carry it everywhere the way that you do an iPhone or iPod Touch. Two examples that look a little ridiculous when scaled up to iPad size are a compass and a calculator.
The situation isn't likely to get much better until a big chunk of laptop users start adopting iPads as their primary portables. At that point I could see a lot of web apps start to make native-code interfaces.
In fact it might get worse once iPhone-4-optimized apps can be run full screen on the iPad complete with non-pixellated graphics and text.
So that leaves productivity apps, games, and a few miscellaneous categories.
I'm about to start porting my iPhone "Brainstormer" app to the iPad (along with an overhaul of the editing UI). It doesn't seem like it's going to be that much work but we'll see.