The most important thing that I learned was that it really isn't all that intimidating to do all this stuff. For me the hardest part was actually getting logged onto each site. This exercise increased my confidence to explore these new technologies.
Most challenging was actually signing on. My first attempt to get an email account was frustrated by being thrown into a Google beta test of some sort. Once I got past all the idiosyncratic logins and password stuff, it was much more fun.
Certainly libraries can use these sites to communicate in alternate ways to the folks who prefer these venues, or are constantly logged in or logging into these social networking sites.
The module was well-designed. But for non-techies like me, it was indespensible to get help from fellow employees. That in itself was a good feature.