Alright, turns out SQLite was infact the source of the memory leaks. More specifically, the Tcl extension to SQLite.
I built the latest CVS version of TclSQLite, which includes a fix for a memory leak discovered shortly after the release of SQLite v3.2.1.
http://www.sqlite.org/cvstrac/chngview?cn=2435
You may download the updated libraries from here:
http://www.ioftpd.com/scripts/script.php?id=167
Edit: I posted the wrong ones, please redownload them.