Social Networking sites have been given a bad name on the news and in schools. These sites do have value to professionals. As a librarian, I can have questions answered and people can give me advice in seconds. I can also provide assistance in seconds. Gone are the days of being on a listserv and waiting for email responses that may never come. If I don't get a response on Teacher Librarian, I can try Twitter.
Library Thing and Shelfari are great for readers advisory. Even though a librarian's job description has more and more technology related duties, we should still provide reader's advisory. My students and colleagues can click on my bookshelf and see what I'm reading. If I am reading books about an educational trend that they are interested in, that could be my inroad to collaborating with that teacher. See? They're not so bad. Just use them correctly and many doors will be opened to you.
Clarification of Fair Use Guidelines of the Copyright Law
Finally The End To Copyright Confusion Has Arrived