*bump* any update on this?
For the truly OCD people there are two choices that are much simpler than modifying the bitcoin client:
1) write a C/C++ wallet cleaner utility using the matching Berkeley_DB libraries
2) do db_backup/clean/db_restore using Berkeley_DB utilities. The backup format is textual and the wallet database structure is very simple, so the "clean" step can be written in any of the widely known text processing languages like awk or Perl.
Remember that when using Berkeley_DB utilities you may need to create an appropriate DB_CONFIG file to be really on the safe side. This was discussed before on this forum.