[fookyong]

as you said, that's pretty much a recipe for an unstable business.

3rd party platform + a feature that everyone wants + makes money... it would make zero sense for the 3rd party to sit on their hands. you're either going to be acquired (lottery) or, more likely, they will implement the feature on their own and you'll be both out of a revenue stream and have a piece of obsolete software on your hands.

good for hackers with ADD and I see nothing wrong with building this kind of thing for teh lulz etc, or to promote your real app.

very strange when you see VC-funded "features" though.

[iamclovin]

Even Foursquare/Gowalla look like features which can be out of business by either Facebook/Twitter

[fookyong]

My mind boggles at Quora too. I just don't get how they can even think of launching while Facebook are about to roll out their own Q&A feature.

The StackOverflow folks have the right idea - I think the market can support a bunch of niche Q&A sites with tight communities.

For monolithic Q&A sites on every topic under the sun, you need massive traction otherwise you have the usual chicken/egg UGC problems that we've seen a million times before. Facebook already has massive traction, Quora doesn't. Game over.

[qq66]

Q&A sites don't need a lot of users to be effective. Any group of 500 people can probably answer a question that you have, unless it's very arcane. User engagement is much more important.