Just curious especially about you Rails folks on EC2, what's your production setup like and what do you use for deployment? (Capistrano, Chef, PoolParty, Rubber,etc..?)
I run some PHP/MySQL web apps on EC2. There are a few high-CPU medium instances running the web servers behind a simple load balancer, and a large instances running databases. I don't use any extra tools for deployment, just checkout/update from the subversion repo. Some rules in httpd.conf block web access to the .svn folders.