This question immediately attracted my attention because I was pretty sure I knew the answer off the cuff. Checking my facts a trivial Google search confirmed the answer I was going to post.
Does this sort of stuff belong on the site or am I being obnoxious?
Update
So it seems my confidence in the March 1st 1945, 1st Warsaw Cavalry Brigade charge being the accepted "last cavalry charge" may be unfounded. In this case I think it has value, assuming it results in an answer that provides a more recent example.