Also - could lead to a targeted-groupon like business model (in your circle of friends, 2 people have said they really want to come to our restaurant. Convince 10 people and get 20% off! Someone's friends that already like a product are probably the best word of mouth you can get). Or advertising could be much better targeted if you say what you're planning on doing instead of what you have done.
I had an idea like this once (and gave up cos I thought it was unlikely I'd pull it off - and I think I have a more reasonable idea to execute on) for a social-network travel agent. If you have hundreds of people giving you advance notification of their desires (I'd like to go skiing, for < £800, anywhere in the alps, with this group of people), travel agents could do collective purchases like booking entire chalets / chartering flights (a la Social Flights which also just hit HN headlines).
A lot of people have probably looked into social planning, but no one has done it very well so far. The execution is going to be all that matters with this, not the fluffy pitch about "social" and all that gunk.
the trick will be curating or culling the feed, we all have a lot of FB friends
I might have 300+ friends on Facebook, but really, I like to spend time with maybe 10% of them on a weekly basis doing these type of activities.
You're correct and I get your point. My first statement didn't get out as intended. I think that with those services in its current form it's not so much about where it is now, but where it can get. Ofcourse you don't go out with the 300 friends you have on facebook. But those services aren't focused on such big networks; they are focused on the 25 people you do and can go out with and it is about sharing valuable information and having fun with those. Facebook is great for the 275 other ,,friends''. The network is smaller, but it's really more social.
dodo53 and useflyer's comments do a good job at explaining how WhereBerry is different from a calendar.
WhereBerry is helpful for capturing ideas that aren't fully formed events yet – simply things you'd like to do. In fact, a lot of our items don't have a set date (movies, hikes, restaurants...). Once you know who's interested, it's easier to pick a date and organize it.
Re:curation, for now you can unfollow people who post activities you're not interested in. As we get better data, we plan to add relevance ranking so manual trimming becomes less necessary.