One thing to be aware of if you are compiling on VS 2005 for deployment on linux, is that the MonoDevelop solution leaves out some things like web parts from the build because they are not yet supported on Mono but the VS solution does not remove these things.
In order to help make VS 2005 compile a correct build for Mono, you should add MONO as a conditional compilation symbol. Right click the mojoPortal.Web node in Solution explorer and choose properties, then choose the build tab to see where to add this.
The fix for the memberlist specifically uses this in code, ie:
The MonoDevelop solution has this setting already but the VS solution does not.
Glad to know your mojo sites have been running well!
Any testing at all on Mono is very helpful, just keep reporting any issues you find. I have a forum just for Linux/Mono issues that is the best place to report them.