For those who weren't able to attend Microsoft's Professional Developer's Conference this past week, Miguel gave a presentation (wmv) about Mono detailing some exciting new developments.
For example, Mono 2.2 (slated for the first week of December) will have a C# shell which Miguel and Marek have been working on and which Microsoft has announced will be part of C# version 5, slated for release sometime in 2012 (yes, that means Mono is ahead of Microsoft!).
Also presented was Mono in video games, such as those on the Wii and iPhone platforms (which are both supported targets of the Unity3D game development studio). Some game studios are apparently also using Mono on the PlayStation3, Xbox360, Windows, and Mac platforms. The main interest here was that Unity3D has been rewritten from Objective-C (on the Mac platform) to C# which should make it eventually portable to Linux (C# version now runs on Windows and Mac).
Another interesting development that came about because of interest in using Mono for video games (since some game development studios are now writing games in fully managed code), was that it was important for Mono to get SIMD support which has now been implemented and will be available in Mono 2.2. This has made Mono extremely fast (up to 10x faster) with respect to 3D vector math and other areas that benefit from SIMD.
This is really exciting!