Despite failing to set the world alight with 2011's ChaCha and Salsa, HTC and Facebook will collaborate once again to bring another Facebook phone to market next year, according to reports from Bloomberg. Details on the purported device are scant at the moment, but the report, which cites the usual "people with knowledge of the matter," indicates a mid-2013 release, after the launch was apparently pushed back from the end of 2012.
The site doesn't mention Android specifically, but we'd be surprised if Google's OS wasn't involved in some way or other, given the history of collaborations between Facebook and HTC. Bloomberg says the phone will run a "modified" operating system, which suggests to us that we may see a forked version of Android, similar to what Amazon's done with the Kindle Fire. For the less technically inclined, that means a version of the OS built upon the open-source code, and most likely excluding any Google apps.
Android followers will remember that last year's HTC ChaCha (aka AT&T HTC Status) and its Europe-only sibling, the Salsa, weren't met with much success. So it's possible we'll see the two companies adopt a different strategy this time around. With Facebook getting more involved in the app space, it'd make sense for the Facebook phone to be heavily invested in this, rather than something like Google Play.
In any case, it seems the rumored device is still the best part of a year away from completion, so it's possible we'll see more changes throughout the course of development.