Thanks to Jens Kraemer for sending me a copy of the ferret_ext file I was requiring to get my search working.
Maybe upgrading from Ubuntu Breezy to Dapper causes a few problems I hadn’t come across before. I’ll need to try a fresh install of Dapper, and see if compiling Ferret works on that.
I’m now running Capistrano, a very clever set of Rake deployment scripts for rails. Being able to commit a revision to the live server, and revert to the previous version if it all goes wrong is brilliant.