Sharepoint user display name doesnot change with the AD changes.
Check the status of the sync:
STSADM -o sync -listolddatabases 0
check the timestamp that shows the sync. If not in sync follow the below.
- Go to SCA -> SSP-> User Profiles and My Sites -> User profiles and properties
- Start the full import to synchronize the chagnes in the AD or to remove the un wanted profiles. To update the Profile info with the new changes in the AD, just go for the incremental update.
- Click on the import source or import schedule link to get the Configure Profile Import page.
- Click on the "Refresh" to affact the changes.