Snow Leopard install went fine. Running methodbox after this didn’t. ImageMagick, libxml and mysql gems were all broken. Followed this advice to get it all working. Boils down to re-install MacPorts, install ImageMagick and libxml2 from ports, re-install the RMagick and libxml-ruby gems, install mysql-64bit, re-install mysql gem (in 64 bit mode).
Easy!! Only took 2 hours. So that’s about 4 hours (and 2GB+ downloads) for the snow leopard upgrade so far!
Also found this script for installing ImageMagick. I couldn’t get it to work but maybe you can.