Personally I reckon you should focus on creating a truly awesome FB client. There's already way more Maemo 6x Twitter clients than there are FB ones. There's that good S^3 client (name escapes me) that does multiple social networks. But it's Twitter utility/usability is now falling behind some of the best Twitter clients. You spread yourself thinly & you run the risk of not being very good, just mediocre at more things. Maybe longer-term you could integrate some sort of compatibly with Diaspora? It's much more like FB than Twitter, just a more "FOSS friendly" version... Google+ client may be a good idea too, but IMO the hard focus must remain on FB. Unless you feel you can branch out & still maintain very good utility/usability for everything.