Google Lawyers Admit To gmail Privacy Leak
 

So, as can be expected, lots of these advertisers have Gmail accounts. And what did Google do? It checked them. Google algorithmically peaked at all the accounts on the list their agent had developed which they had access to, to see if the mail was marked spam or not. There were 75,000 accounts in which it was marked spam, and an unknown (larger) amount of accounts must have been compromised to get that statistic.

Is that why there was so much spam lately?