hi rob,
no worries. just about every software developer installing oscurrency has little to no ruby experience.
ruby 1.8.7 and rails 2.3.11 are the versions.
it is generally easy to set up without heroku but you will need a few minor code changes to serve images from the filesystem instead of S3. however, heroku will save you a lot of time in maintaining your system with all of the free services it provides.
as of 4 weeks ago, memcache was added to the groupy branch and this makes a huge difference in performance. only parts of the system are using it now but more code will use it in the near future.
jump on #oscurrency on freenode irc or you can contact me at herestomwiththeweather on gtalk if you like.
cheers,
tom