What makes this even more problematic is that a lot of your FB info is public. Such as your first name, your list of friends, your hometown. So spammers can personalize those spam emails very very well than normal spam. Imagine a email subject that says "Hi <NAME>, <FRIEND'S NAME> referred me to you!"

Facebook's new massive email list is another thing to segment and sell off to advertisers, and another way to make money from its users.

I can also see partnerships with anti-spam and anti-virus companies. Maybe users will need to subscribe to these in order to maintain a sane inbox (and FB will get a slice of that revenue, natch).