I loaded up FW today (after a long period of not using it) and noticed that
none of the "bsae" library assets are shown. The Is there an easy way to
re-import these so that I get back the nice organization of
Mac/WinXP/Flex/etc.. that was there when I first installed FW? Or am I going to
have to re-import each library by hand? If so, which file should I import? The
PNG or the JSF file?

Figured it out. Looks like last time I used FW I accidentally closed the Common Library window and forgot about it. Going to Window -> Common Library popped it right open.