I restrict my blogs to just allow posts from registered blogger accounts. Still every post on our Curious Cat Science and Engineering Blog gets spam posts within minutes of being posted (for some reason that blog gets more than 75% of all the spam comments - the others only occasionally get spam). I can't believe Google can't block most of these bozos. I also can't believe they don't give us the option to only have comments posted once we approve the comment.
Google really needs to upgrade blogger in several obvious ways. I can't believe how slow upgrades to blogger have been. When I decided to go with blogger for my blogs I figured, ok there are some really lame things (like not being able to categorize posts) but Google just bought blogger so I am sure within a few months these obvious shortfalls will be fixed. I am still waiting. Overall Google is doing great things but I really think they should be doing a better job of improving blogger and of providing less spamy search results.
They don't even make it obvious that they pay attention to the comments I delete (maybe they are doing some analysis of what all us bloggers are deleting but I don't know...). They should have a button that says deleted because this is a spam comment. Then they could use the collection of such decisions by bloggers to deal better with spam.