it's an increasing problem on MT blogs - I've read far too many reports like Bill's and Byron's recently. There is a MT plugin available, but I don't see how that would stop a spammer with a non-static IP.
Personally I plan to stick to Blogger forever. The fact that Google now owns the company excites me, I'm eager to see what new features they innovate. And I'm fine with using Enetation or Haloscan for my comment system, since they seem to be immune to comment spam for now (though Enetation is famously unsteady at times).
Here's my ideal comment system.
- required registration. Add a password field with email verification to make sure that commentators are valid. Email validation, not IP address, is the true guarantor of identity, and adding the registration step also does filter out the riff raff (not that there's a problem on UNMEDIA, of course. I often wish I had more comments here). Registration also simplifies user management issues like banning.
- data should be stored as an SQL database. There are only a few fields in the table, after all: username, email, website, Full Name, and Comment Body Text. With the SQL backend, there should be a query facility built into the interface so that you can do complex searches through the comments easily. This would also facilitate cool sidebar features like "Most popular commentators" and "Latest N posts on Topic Z"
- Automatic import of the parent blog post into the comment system, so that it doubles as a blog backup. After all, the same fields exist for blog posts as they do for comments. The database should work with teh Blogger API so that the Publish button can also directly import a blog post into the comment system as a top-level entry.
- Discussion forum view - since the parent blog post is stored in the system also, the entire thread - post and subsequent comments - are identical to the discussion forum paradigm of a thread post and replies. The comment system should allow you to query for a given blog post and return that post and attached replies formatted in the classic forum interface.
- Standard blog post view - all the comments attached to a given blog post should be accesible through a single iframe within the blog post itself - a single line of HTML provides the full comment history as a scrolling subwindow without the need for a pop up.
Think I'll submit these ideas to the Blogger Dev folks...
UPDATE: It's hit Jonathan, too.