Mac OS X,  Unix,  Windows Server

Mono 2.0

Mono 2.0 allows .Net developers to use Linux, Solaris and Mac OS X.  Mono comes with MeMA, a tool that allows for automated .Net to Linux migrations away from .Net.  A lot is being made these days about Silverlight.  Look at what our friends from NetFlix have done for Mac users with it.  Well, the Mono framework was leveraged to write a Mono-based plugin compatible with Silverlight that they are calling Moonlight.  This is pretty cool because it allows Silverlight developers to convert their code into Moonlight and then publish it as an actual desktop application rather than a more web-oriented widget.  The open source community has provided a really great tool yet again.