Version 1.4.2: works with TextMate 1.5.7. If you are using TextMate version 1.5.7 or later, you will need XMLMate 1.4.2 or later. Earlier versions of XMLMate will not work with TextMate 1.5.7 or later. I've also added a user default for making the XMLMate panel a non-floating window:

defaults write com.macromates.TextMate XMLMateFloatingPanel -bool NO