That's a bit different; this is about user-controlled SIMD instructions, not whether .NET can use SIMD instructions as part of its routine JIT code generation (see http://blogs.msdn.com/b/davidnotario/archive/2005/08/15/4518... for some very old commentary on where .NET took advantage of SSE instructions in its code gen).
Awesome! The other day I tried to find the amount of per-cpu tuning the .NET runtime was capable of but could never find anything. Thanks for the link, this is exactly what I was looking for.
https://bugs.openjdk.java.net/browse/JDK-6340864