It depends what you want.
Yes, that's not very helpful, I know! As a born-again geek I've been dabbling in the social software pond, trying to make out whether any of it is useful to me. What is social software? Wikipedia's definition is 'a range of web-based software programs... [that] allow users to interact and share data with other users'. Examples are MySpace, Facebook, Flickr, YouTube. So I have a Blogger, MySpace and YouTube account (don't panic - I haven't uploaded any videos!). Do I really need more? Probably not, but that doesn't stop me looking!
Follow the crowd
One of the other things I've seen around is Twitter. This is a 'micro-blogging' service that allows you to update people in your circle of friends to know what you're doing. You can use the web, mobile phone (using SMS) or IM (Instant Messenger) to update your 'Twitters', so you don't need to be near your computer or a WiFi hotspot. Sounds great, doesn't it? Going to be late - Twitter (or is that Tweet?) your gang and let them know. Need help with directions/a phone number/putting the cat out - Twitter and you're done. And yet....
You need a life, first
There is no meaningful way for me to use Twitter, apart from finding out what other people are doing. And if I'm not updating and simply watching other people, isn't that a bit, well, weird? Does it make me a stalker? Perhaps...Now, other people use it the way it supposed to be used and get all the benefits. Wil Wheaton and Felicia Day both use Twitter, and seem to find all manner of uses for it. There is a great Blog article from Doug Belshaw about Twitter and whether it is a good or bad thing. I wouldn't have found it if I wasn't looking up about Twitter, so in that way Twitter has done me a good turn. Mr Belshaw writes excellent Blogs about technology and education that are well worth a look.
So Twitter - useful or not?
I'm sticking to my original position. I've got enough to do without adding more things. Whether you might need/want/benefit is up to you. I've got a Twitter account but no plans to start micro-blogging. How about you?