Twitter, like MySpace or Facebook, is toy-like. It does not provide clear, definable value to the world it lives in. Yes, Twitter is able generate a tidy profit thanks to the rivalry between Bing and Google. Clearly, we should be dancing in the streets over this (not).
And like MySpace and likely someday, Facebook, Twitter will find itself being left behind for the next “big thing.” MySpace likely thought that it could not lose. Now you cannot bribe people to sign up if you tried.
No, I would agree that Twitter is clearly turning a profit, but fame is fleeting and Twitter’s could easily fizzle out if it is not careful. I’d like to see Twitter taking a more Facebook approach to outreaching with developers, perhaps build up something of value besides its API and good intentions.