Not much. Most users won't even notice a difference. Everything is pretty much just bug fixes and updates. If you plan on doing stuff with any of these areas:
- backup to tape
- pptp connections
- using smp kernel
and several other minor bug fixes, then you should upgrade to 4.1.1. Check the updates directory under the 4.1 directory on your local mirror to save yourself some time in doing the upgrade.
There should also be an article posting about these differences on the .org site soonish.
Regards,
Jason