Facebook is now doing a massive clean-up by deleting thousands of fake accounts, since they are now implementing the Integrity System which was announce a month ago. Well, I agree with it, it's good for future security precautions. Knowing that Cybercrimes is very rampant nowadays. They should be very cautious more indeed.
By removing those illegitimate accounts, a lot of businesses having Facebook fan pages we're greatly affected. Though it's not clear how many accounts have been wiped out, but a lot of pages have seen massive drops in their fan numbers. And we can see some evidences like for example, Zynga's Texas HoldEm Poker, one of the most popular games on Facebook, had lost 96,000 and still counting, though it's just a small percent of it's overall total. Also with the other top fan pages like from our favorite artist, etc., they as well we're affected.
Though Facebook haven't announced it yet, about when will they be finishing doing the clean-up. Because I know that it will take time cleaning it all, and it's not that easy since they are now expanding fast paced, so in short, they will be handling bigger databases. :)
Nevertheless, Facebook has gone so far in terms of fighting spam that greatly reduced spam by 95%.