I’m not a heavy user of Subversion, so forgive me for not being part of the prevailing “use the command line” crowd recommendations in OS X (and probably most Unix/Linux users as well).
I was using SmartSVN for a while – so long that the open source version I was using seems to have been replaced with a commercial version for $79. Not a bad price for a heavy user, but I’m an extremely light user. My old SmartSVN version was not dealing well with the file constructs in OS X for an application. It had always worked fine when I was just editing PHP, HTML, or XML files. But, it was breaking trying to maintain the application links so I looked for something else. Here was my start: http://theappleblog.com/2009/02/23/12-subversion-apps-for-os-x/.
I didn’t bother with the cross-platforms and the commercial ones, but the SCPlugin one fit my needs immediately so I didn’t look further. First, free and open source. Second, comes from Tigris.org, which I’ve used for a long time and always liked their site and forums. Small download, drag and drop install. Installs directly on to the Finder tool bar.
I haven’t quite figured out how it knows where the server is – it “learned” this from a folder already in control of Subversion for my first try. But, I like the Finder integration and it seems to work well. No problems.