For those interested, I've been working on a Poly/ML package for Sublime Text 2.
https://github.com/akissinger/sublime-polyml
Sublime Text 2 is in some ways the "moral" successor to Textmate (which is essentially defunct). However, unlike Textmate, it's available for Mac, Linux, and Windows. It will be a paid app at some point, but currently it is in free beta.
I've been using the package for a couple of weeks now. It's still a bit on the rough side, but basic highlighting, building, and error reporting is working pretty well. Please let me know if you have issues or want to contribute.
Aleks