Facebook, itself the speculation of a lot of M&A, has done its first small one: it has bought Parakey, a still-in-stelth startup run by Blake Ross and Joe Hewitt, co-founders of Mozilla Firefox. The two will work on the development of Facebook Platform and the site. Financial terms of the transaction were not released.
Parakey had seed funding from Sequoia, and has been in the works for a couple of years. It is an online OS, something which Facebook could conceptually be called, at least in terms of all the apps being resident on it and user time-spend. On what Parakey is/was besides the generic description, read this details IEEE Spectrum story. Details on acquisition in release.