They've got a rock-solid cash position, and I wouldn't be surprised for Marc Andreessen to re-invest after 2 years, just to own a piece of this flex infrastructure for such a small $ amount.
Today's announcement is exactly what's next.
Building more ways to "roll your own social network".
The API is amazingly rich - the developers love it.
For example, messaging is far beyond Twitter's broken DM mechanism. The API allows you to DEFINE messaging protocols, and uniquely build a social network with a distinct message system. It's software-definable, via the API.
What's actually happened in the first 5-1/2 months is that the "core API" is finally finished. They've actually unbundled all the core social 2.0 infrastructures.
Watch for more creative "edge API" ideas (like this social Dropbox) to come out, now that the core team of 14 is freeing up to invent.