Does the .NET CLR Really Optimize for the Current Processor

Question

When I read about the performance of JITted languages like C# or Java, authors usually say that they should/could theoretically outperform many native-compiled applications.

Answer 1

From back in 2005, David Notario listed several specific targeted optimizations is his blog entry "Does the JIT take advantage of my CPU?". I can't find anything about the new CLR 4, but I imagine several new items are included.