Marco van Hylckama Vlieg, a.k.a. i-marco, has written an open letter to the people at Google. Topic of the open letter is his, and with him most bloggers', frustration about comment spam, trackback spam and referrer spam. In his letter, he makes some good points about comment spam and the importance of Google in this. Though the nofollow attribute is a nice addition, in the long run it won't make a difference, because by far not all weblogs will be secured with this tool.
I definately agree with marco's points, and I sincerely hope that the Google crew will respond to this open letter. I hope a discussion will be started here about how to stop comment spam, with the most important party in the whole comment spam, Google, openly joining this discussion. After all, Google is the main reason for comment spam to happen.