Actually, as the platform itself has been standardized (ECMA 335), it is not the platform that is hard for them to create. The hard part is recreating the extra libraries, not part of either the CLI or C# standard that MS bundles with VS.
DotGNU is making pretty good progress. Their status on the libraries is available at Portable.NET Status Page. Mono has been working on this as well.
To some degree they will always be playing catch up--recreating the libraries as soon as MS puts them out. However, this isn't the impossible task that Win32 was.
Bingo, which is what I was explaining to him. I think he got it but thanks for backing me up.