Like I said, I think the market for simple applications is probably saturated and now is the time for Ruby and Rails to go up-market and tackle bigger problems. We’re well equipped to do that, having learned from what sorts of simplicity help reduce tricky problems to tractable problems.
In my RailsConf Europe 2008 presentation, I play the role of the messenger. I’m not bringing any new science that makes building more involved applications easier. Instead, I’m trying to tie it together into an understandable package. You take the gems described herein (money, acts_as_state_machine and acts_as_versioned) and a couple concepts (domain driven design and queueing) and you can build some really cool applications that solve pretty tricky problems. To me, that’s big fun.