I've noticed that MT keeps adding an image (nav-commenters.gif) in some directories altought I've disabled comments on every blog, and my templates don't have any comment tags in them. I keep deleting the image, but MT keeps putting it back when I rebuild. Anyone else noticed this? And is there a way to fix this?

It's used with a new MTCommentAuthorIdentity tag that provides a link back to a users TypeKey profile. It's generated every time you rebuild your blog.

I think it's kept separate from the other CMS images because it's used on the blog which could be somewhere different from the CMS. They could have linked to a nav-commenters.gif on typekey.com but I have a feeling the privacy implications would have upset some people.

Regenerating the file in the blog's site path is probably the easiest way to make sure that links to TypeKey Profile are available. (Although it seems like a text link would suffice)

Unfortunately it doesn't look like there is an easy way to tell MT that you aren't using TypeKey and to turn off the image generation. I imagine this will change when the release version comes out.