Funny you should mention that, I only found out about them the other day.

In theory SVN::Web could support these. I'm a little concerned about the performance hit -- SVN::Web doesn't have a working copy, so every time it needs to query them it will need to walk back up the directory tree until it finds them set. It could cache the result, but I'm not sure how long it should be valid for.

There's a discussion about this happening at http://markphip.blogspot.com/2007/01/integrating-subversion-with-your-issue.html, please feel free to join in.