The MGTwitterEngine is available from Matt Gemmell’s public subversion repository.
I have used IBM’s source code management (clearcase), but I haven’t used Subversion.
I’m going to read up about it and and use it on my macbook for new software projects as well as to explore using SCM for novel writing. [NaNoWriMo is coming up in November]
I just started using git, which has been gaining popularity (Linux kernel, Rails, etc…). It’s kinda quirky at first, especially after using subversion for so long, but I’d definitely take a look. There’s a google tech talk floating around that explains all the benefits of it; it’s definitely worth checking out if you’re shopping around for an SCM.