Great analysis Bobby. I agree with the general opinion that this seems a bit frivolous at first glance. However, I wonder why they wanted to call it Teachbook after all. To see what I mean, imagine if there was no facebook. Then consider you were going to start a social network for teachers. Would you call it teachbook? I doubt it. It doesn’t make sense. I might call it teacherslounge or something like that, but the book portion is nonsensical without facebook having come first.

That said, there are a lot of better names to go after first as noted by TechCrunch (particularly facesbook):

http://techcrunch.com/2010/08/26/facebook-placebook-teachbook/