Guy Kawasaki has a good analysis on the acquisition.

The bottom line is that it’s way too early to tell. The Twitter developer community will bifurcate: “Hallelujah, you’ve shown us the path!” and “How dare you compete with me?” But don’t forget this: Twitter can do whatever it wants, and developers can lead, follow, or get out of the way. That’s just the way it is in the real world.