Like Kleps, I'm seeing a substantial uptick in spam comments that are getting through Google's spam filter on the blog. Historically, the filter has been very good at its job, but recently the upper hand seems to have gone to the spammers. This is a problem because the one thing Google's spam filter has NOT been good at historically is wasting my time by sending me emails to notify me of comments that it subsequently put into the spam filter (meaning that when I spend my time to go check, the comment is already gone). I get 20 emails per day containing spam comments and until recently none of then had been getting through, but now I'm coming back a few days later and finding that 10% are - which adds up to several spam comments on every post.
I'm disappointed by this outcome because I personally am not a fan of being forced to log in to share my thoughts, and I've gotten some very insightful comments from anonymous readers over the years. Unfortunately, the signal to noise has just gotten prohibitive of late.