It would be nice if Craigslist created a platform that others could build on. Something like Facebook. http://apps.craigslist.org/mapper. I bet people would build things on their data for free even without any way of making money off it.
Oh wait.
*Miscellaneous fees for job listings in some regions, and brokered apartment listings in NY do not apply. Ask your doctor for details. Void where prohibited.
Except craigslist almost is a charity... for it's users.
It's the multi-million dollar business that provides services valued at billions of dollars, previously.
Craiglist indeed barely changes but as one of the largest sites on planet that gives you stuff with barely any bullsht, there's little reason to pine-away for that innovation, if you're someone using the site*.
If coolpads or whatever wanted to just volunteer their Ajax to craiglist and get a share of milk-and-cookies craiglist's thirty employees live on, cool. Otherwise, wipe those dollar signs out of your eyes. Go make the big bucks doing SAP consulting or something.
Padmapper provides a service on top of Craigslist: it maps Craigslist ads. It does not provide classifieds, and Craigslist does not provide mapping. There is no overlap. They are not competing.
Maybe they will compete in the future, but that's just because Craigslist isn't making any effort to provide a mapping feature.
That said, Craigslist UI is terrible for finding apartments, and Padmapper is a fantastic improvement, so I'm very unhappy with this development.
That's especially true for Craigslist. A couple years back Craig and the Craigslist CEO were in front of an audience of Wall Street investors. They were asked, "How do you plan to maximize revenue?" Their answer: "We don't." Which is basically like asking the pope if those little crackers taste any good.
Craigslist is a mission-driven company. I think they've made a mistake, and that they'll realize it shortly. Perhaps by doing exactly what you suggest.
You could try to replace Craigslist using only variants of the code shown in the original Rails screencast, with no consultation allowed. But you'd fail, because the result would be (from a UX perspective) better than Craigslist.
When people find a forum in which to post classifieds, they have exactly one (1) overriding goal: find the forum with the most vibrant market. There are a million zillion little things Craigslist can do better, but they are unlikely to make a big impact on that (1) goal, because Craigslist is already so vibrant that it has mostly put the rest of the classifieds "industry" (ie: newspapers) out of business.
There is really very little in common between renting or selling a house (which Craigslist is only good for in SF/SFBA, and ok in some college or other major-metro markets), selling small, highly standardized items (used iPhone 4s), selling used cars, dating or prostitution, and selling sofas. The unprofitable ghetto is selling sofas, and craigslist is the right place for that.
Amazon marketplace utterly destroys craigslist for selling most standardized, current-production items (books, electronics). There are Apple specific marketplaces for used Apple stuff which are by far the best. Etc.
Mostly because their interfaces are even EASIER for buyers than Craigslist. When I buy a used book from Amazon, it's zero friction, includes all the reviews for the new book, and has a single-button to buy (using stored payment, and shipping info, and shipping in 1-2 days for free).
In essence, the way to take market share from Craigslist is to take any market Craigslist dominates, and reimagine it as something other than "classified ads". It seems like you have to compete with the whole concept of "classifieds", not Craiglist.