"What are they going to do, hack in System.IO" System.IO works very well on Linux/Mac right now. It was one of the first things implemented by the Mono team.

"What are they going to do, hack in System.IO" System.IO works very well on Linux/Mac right now. It was one of the first things implemented by the Mono team. Having ported numerous .NET applications, all of which do fair heavily file I/O (the most common use case for System.IO), the main sticking point has been code that deals with filenames and paths. As in "/home/billy" vs "c:\Users\Billy". A hour or so of cleaning up your code and making use of Path.DirectorySeparatorChar and IsRooted is all I've needed to do. "As it stands the .Net framework/libraries are very Windows locked" This shows a lack of understanding of the .Net framework. Yes, if you used crazy Microsoft specific WCF libraries for networking protocols instead of industry standard stuff, or used WPF for graphics, that going to be a problem. But there are literally thousands of classes providing a fairly comprehensive set of data structures, network protocols, etc that are completely untied to Windows or Microsoft. If you are using something in System.whatever you are pretty OK. P.s., Sockets aren't in System.IO, they are in System.Net