The matter of revision numbers is a bit complex.
All branches of XBMC share the one SVN. When ANY of these receive an update, the revision number of the SVN goes up.
T3CH build archives (as in, the RAR/ZIP files that contain the files) are labeled according to latest
Xbox branch revision number at the time of compiling. All you need to do is look at the revision number in the archive name, and you've got the exact figure. Easy.
The SSHC build archives are named according to the very latest SVN revision number. They will only be accurate for
one particular branch within that SVN, and there's no quick way to determine which one that
is without looking at the
SVN changelog.
Now you might be thinking, "why not just run XBMC and check the revision number it reports?". Well, the reason for THAT is, builds from r18953 through to r28565 get it
wrong. Sometimes they're hundreds of revisions off, so getting those particular builds of XBMC to tell you their revision number is pointless.
To determine the revision number of an SSHC build (using the Xbox branch as an example, for rather obvious reasons):
1. Check the SVN number in the archive title.
2. Take this link, put your revision number from the archive title in place of the X's, and load it up:
http://trac.xbmc.org/log/branches/xbox/?rev=XXXXX
3. The top entry in the list that appears is the actual Xbox SVN number.