From the '.NET on Linux' files:

I've been following the Mono project since its 1.0 release back in 2004 and a lot has changed. Today the project released Mono 2.6 providing even more features and compatibility for developers looking for a .NET framework implementation for Linux.

The 2.6 release is the first major release from Mono since the 2.4 release in March. There are a number of new items in the 2.6 release but at the top for me is the continued evolution of Mono's overall performance.

The other key item that Mono continues to improve on is compatibility with .NET itself. With 2.6, the release notes state that they've achieved more complete .NET 3.5 API coverage, which in my mind is a good thing. Mono has always tried to include the most important elements of .NET, but has not had them all.

The 2.6 release also includes a new verifier and security sandbox which comes by way of the Moonlight effort (delivering Microsoft Silverlight framework compatibility on Linux).

Oh and did I mention that Mono 2.6 includes - wait for it - Microsoft's open sourced ASP.NET MVC. Microsoft announced back in April that the MVC stack was going open source, so it makes sense that it would end up in the open source Mono project.