I too am interested in using Subversion with maintaining the latest stable update(s).
I had a copy of 1.5.1.3 but did a svn switch to https://svn.automattic.com/wordpress/branches/1.5 to get the latest 1.5.2 update (no tag for it yet).
Is there a documented changelog of what stable release corresponds to what revision in the repository? If not, where can we request this?
Thanks.