[Begin Edit]
When I originally posted this, the original post was all that was showing. So forgive me if it seems to ignore points brought up since then.
[End Edit]
I'm not convinced that it's impossible yet, but I tried compiling #Develop with Mono and ran into a few snags. The biggest snag was that the *.cmbx and *.prjx files aren't the same format as the MonoDevelop (*.mds and *.mdp) file formats (Close, but not quite the same). MonoDevelop can read the #Develop projects, but wants to convert each one. There's something fishy with the conversion process, though, because all it takes is one error and it tries to reconvert every project again.
At any rate, the problem I've found so far is that one of the projects for #Develop requires access to the System.Data.Query (?) namespace, which Mono doesn't support yet. This namespace *CAN* be found in one of the sub-projects from www.monoproject.com, but that project is highly unstable, since it's constantly changing.
I had planned on either finding a way to convert each of the #Develop projects by hand until each one compiled or just wait for Mono 2.0 to be released. I'm hoping that once either of those occur that I will have #Develop up and running. MonoDevelop is nice, but it just doesn't do what I need it to do. I work with Visual Studio 2005 all day long at work, so MonoDevelop is severely lacking when it comes to this.
I guess we can all just cross our fingers and hope that someone from #Develop will fix it so that it will compile with Mono 1.x :)