One of the great things we haven't really touted with this release of nGallery 1.6.1 is that it now:

This is something we on the nGallery team are very proud of! Ken worked closedly with Vlad and Miguel working through the issues that we had, and I think the Mono guys even found a few things that nGallery helped uncover.
A few things to keep in mind for those of you wanting to be Mono Aware:
Rule #1: Never, ever, ever use the \ to seperate directories when doing any file I/O. Instead, use the System.IO.Path.DirectorySeparatorChar constant. This translates directly over to the *nix world and makes for a smooth transition in Mono.
Rule #2: Just as most of us have learned case sensitivity in .NET, carry this forward to your file I/O operations, again, and make sure all files and directories are case sensitive.
Rule #3: Make sure you don't compile your assemblies with the /incremental flag. Mono can't support incremental compilation. For more details on what "incremental compilation" is, see: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cscomp/html/vcgrfincrementalenableincrementalcompilation.asp