It seems that Facebook app from version 2.0 and up (now 2.1 latest) is recoded and fully invertable!!!! Look here for a guy who did a nice job on version 2.0:
Anyway, version 2.1 is out and it is even more invertable as they droped all HTML code out and the app is 100% android original source. i did some testing and modified values/color.xml (inverted back/white) and it worked! Of course there way too many theme related parameters for a noob like myself to handle (many colors are non local and uses Androis's colors). But I'm sure rujelus22 with his experience can easily get FB2.1 fully inverted again. This is the ONLY app that provides full functionality including tagging support and easy access to all camera photo's..
P L E A SE rujelus22 have a look at it and see if you could bring the facebook black magic back...