Just installed the MT 2.661 upgrade.
Fortunately, I had the MT 2.66 upgrade still sitting in my $HOME and so I was able to diff the two and use patch to apply the new changes. It's vastly easier than installing the new version and then trying to re-patch the comments files so that threaded comments and email responses work correctly.
I should probably pull the MT source into my subversion server and use it to merge in changes in the future ...
