This is actually Beta 3 of Mono 1.2, some highlights (according to the official announcement):
IronPython 1.0 Beta 8 works with this release out of the box.
Majorly improved Windows.Forms and System.Drawing as our beta program for Windows.Forms continues.
New default optimizations boost performance for compute intensive applications.
Long standing debugging line numbers bug fixed.
Preview code for the new Compacting GC.
Hardened runtime for verification, AppDomain unloading and type loading failures
Significant progress on ASP.NET 2.0, some Starter Kits are now functional, as well as large improvements to its test suite.
Seems like we are one step closer to SmartClients (TM) in Linux... Go get your copy here.