Forum's enough for me.
Gave up on my Facebook account for various reasons but two of the main ones being I couldn't be bothererd and, even I could, I didn't have the time. I can see some of these things can have a use for some people but for the most part they seem to be filled with dross and inanities as Dom says.
Personally having the one place for everything is a heck of lot simpler. How is anyone going to know there's a 'quick announcement' on the twitter account? It'd be like some of the current awareness checking I used to do at work - sometimes it would be weeks between anything changing and yet I had to keep checking several times a day, just in case...
Not to mention that not everybody has internet or email, even in this day and age....