This may be a stupid question but is there a reason that the version of Support/bin/mate in svn is much much older than the one shipped with the app?
$ svn update /Users/jay/code/textmate/Support/bin/ # My SVN repo At revision 11963.
$ /Users/jay/code/textmate/Support/bin/mate -h 2>&1 | head -1 mate r851 (2006-05-03)
$ /Applications/TextMate.app/Contents/SharedSupport/Support/bin/mate -h 2>&1 | head -1 mate r1577 (2010-11-12)