Not to complicate things, but you could also open the illustration in Photoshop, select everything, inverse, make a work path, export work path to Illustrator, then do some cleanup back in Illy depending on how well your settings in Photoshop were adjusted when you made the work path.
There are probably a few other ways to skin this cat, but I can't think of too many other ones not offered already. I'm sure you could monkey with the autotrace in Illy and get it to do a decent enough job if using the pen tool all the way around everything isn't your cup of tea.