Mark Czubin has begun work on an F# mode for MonoDevelop. Will this become a community project? I hope so!
Mark - for a long time we've planned to include stable and published versions of the F# APIs for interactive lexical coloring, parsing, type checking and intellisense. Plugins for MonoDevelop and other IDEs could use these directly. Would you like to call these if we provided them in the next release?
Cheers!
Don