The Open Source version of .NET has reached the beta stadium. Mono beta 1 it is labeled. Read the Release Notes or go to their Download page.
One of the big things about this release, is that it supports generics in both the C# compiler and the virtual machine. Also Mono has a Global Assembly Cache now and a gacutil-like tool to manage the GAC. Beta 1 contains preview functionality (alpha stage) of System.Windows.Forms as well.
If you need a free IDE to develop Mono programs (or .NET programs, whatever you like to call them), you can use MonoDevelop. It’s currently only at version 0.3, but it gets the job done. It has Code Completion, Class Management, an integrated debugger and built-in Help.
It so happened I installed version 0.31 (the previous version) yesterday, and played around with it. The executables it generates (executed on Linux or other non-Windows platforms within Mono) execute perfectly on Windows without calling Mono. I haven’t tested any difficult programs yet, but this is great.
Apache for Win32 with Mono will release us from IIS while maintaining .NET compatibility and without loosing our favorite Windows programs.