Somehow I missed this but I noticed ZigVersion mentioned in an Apple Developer Connection email recently and that it is now 1.0! Congrats!
I did a quick review of ZigVersion a while back and I have been using the beta version off and on for my own personal projects ever since. It's a great simple to use graphical Subversion client for OS X.
ZigVersion is a Version Control interface for Mac developers that works with Subversion servers. Instead of simply reproducing the command line concepts as a graphical interface, we looked at the typical workflows of professional programmers and designed an interface around them.
Note that it isn't open source and requires a valid license. However, you can use it for a trial period to see how you like it first. I'd recommend they lower the commercial license cost as it's a bit high and might chase off potential customers (particularly small independent developers). They have promised to offer a free non-commercial license in the future.