Tools like Facebook and Twitter can certainly be very useful and a quick way of getting the message across. Also with working in the NHS I can see the great potential and extreme usefulness when it comes to sharing important info such as healthcare. Our library has a Twitter account which we can share information with our patrons via our Intranet page at the hospital - such as informing them of the latest editions of journals. Assuming not all of our users have Twitter accounts it was decided that we should add a feed to our Intranet page.
I think social media has become an important asset in linking up with others. With the likes of Facebook we can discover old friends and maybe re-kindle the flame as it were. On the professional side it can useful to form contacts and also gain knowledge to further one's career.
Social media will never replace actual face to face contact however, but in these times where travel is expensive and a lot of hassle! contact via a computer is very handy and convenient. Also with the web conferencing quality getting better all the time, we can 'meet' people from almost anywhere!
On a personal basis I have only used Facebook for personal use. I have never done conference calling and I have only just set up an account with LISPN. Not sure if it's worth it, because I am not really a 'New Professional'... but I will carry on for now. As for blogging I don't think I will carry this on in a professional capacity for myself, unless my manager wants me to set up one for our library or something like that. I am currently thinking about setting one up for my hobby which is greeting card crafting. I never know who might 'notice' me...