I was recently discussing with rsinger and others on the #code4lib IRC channel, the barrier presented by having to get a ruby/rails stack up to library folks who want to try open source software (like Umlaut!) that runs on ruby/rails.
Just noticed this product: Bitnami Rubystack.
Haven’t tried it yet myself, but the rubyflow posting referenced above claims it offers close to one-click install with ruby, rails, passenger, rvm, and all the other basics you’d need — native install OR in a VM, on linux, OSX, Windows, OR the Amazon cloud. Some option of which should work for just about anyone.
If it works as well as it says, then once you’ve got your stack in a VM, getting Umlaut going following Umlaut’s installation instructions should (hopefully, let me know if not) be a snap.