Playing with Facebook (FB), friendfeed (FF) and twitter (T) at the moment. Have been using FB for ages (like most of the planet) and have had FF and T accounts dormant for a while.

 I typically use FB to stay in contact with a small circle of close friends. I tend not to muck around with the applications as I typically interact with FB via the simple (and now in considerable need of an update) FB Blackberry app (v1.3, 1.5 is meant to be much improved and just around the corner).

 The facelift to FB was ok with me - I prefer the stream of comments etc.

 One thing I don't like in the FB timeline summary (as opposed to how FF do it - these guys appear to be the source of many of the best features!) is that if you comment on a status update it does not go back to the top of the list; which it should in my mind as is the comment atleast is a very recent update.

 The other killer thing I like about FB is the photos and sharing - very slick.

 With FB I've never really got my head around if I can segregate my friends etc - you seem to be able to create groupings but I don't know how this affects your status updates. I.e. there are things I'd quite happily say to my brother which shouldn't really be visible elsewhere!

 I like the concept of "life streaming" as I really want to know what my friends are up to (primarily) with the ability to comment back and forth. FF seems to be very good at this for two reasons: 1) ability to create closed rooms (twitter doesn't have this but it does in Japan I think?) 2) IM access - I can interact with FF intuitively via a variety of sources including instant messenger (this used to be part of twitter - perhaps it'll be back again one day as they sort their infrastructure out)

 Twitter I'm playing with as I think it's a good way to interact with people I don't already know (as opposed to the more close way I use FB). The search is very interesting!

 If FB carry on evolving (aka nicking stuff from FF) then that might swing it for me but how long will FB be around? Aren't they burning a $1,000,000 a month on their web server electricity bill alone? How long can THAT go on for? What's the point in serving 200 million users if you're making no money? Are they just winging it so that as the medium evolves they'll evolve their billing model to fit with it? Online advertising with FB seems to be not doing the trick for them (do we never learn with this?!)

 Very interested in how other people are using these apps.

 Also, do you think FB will be the big player in 3-5 years time? I doubt it...