Last modified: 2008-08-09 23:33:24 UTC
When a user gets renamed, there is an option to move that users user and user talk (along with it's prefixindex) to the new name. This should work the same way for movepage as well.
This was already added to the software quite a while ago. Currently on Wikimedia wikis it's restricted to sysops, for log-spam reasons.
*** This bug has been marked as a duplicate of bug 9626 ***