Vista slow file/copy/delete: fixed?

Seems like Microsoft may have slipped out a fix to this problem.

I’ve noticed that, after running Windows Update on the x64 Ultimate version last week, I no longer suffer from the slow copying problem when transferring files from one drive to another.  Although nothing obvious was posted (the update was marked as a compatibility update for ipod users) I downloaded it anyway. Since then, I’ve been getting transfer speeds of 30-40MB/s - something reaching over 50MB/s - on drives that were previously giving me write speeds in the KB/s.

Have Microsoft finally snook out a fix for this problem, albeit under the guise of a fix for something else?