One problem that I see a complaint about every so often with Movable Type is that you have several independent blogs that use the same URL to get to their trackback and comment scripts. To get around this, I discovered a little trick. Modify your templates so that each template points explicitly to the URL of your blog, assuming it's on a separate domain. For example, change all references to the trackback script to explicitly point to http://www.domain2.com/mt/mt-tb.cgi if your installation of Movable Type is hosted at http://www.domain1.com/mt/. Now, create a symlink between "mt" in the directory that hosts domain2.com and your mt directory under domain1.com/mt. Then, in the root directory of domain2.com, add the following statement to .htaccess (create a file named .htaccess if it doesn't exist):

Options +FollowSymlinks

That's it! Now, whenever someone points to http://www.domain2.com/mt/mt-tb.cgi, it should be internally mapped, without any problems, to http://www.domain1.com/mt/mt-tb.cgi. I tested this out with the trackbacks and it worked fine.