I've watched Heroku for a while. I've even tried to deploy an app there a few times, but never got into it that much. I needed a cheap (free) place to put My Amazon Feeds.com. It's just a utility site. It's not meant to scale or be production worthy. Instead it's meant to show off some code and I didn't want to spend a long time messing with deployment.
Turns out deployment on Heroku is pretty simple if you don't need a lot of custom setup. Their instructions are pretty clear so I won't repeat them. There are a few things you will want to keep in mind:
mislav-will_paginate --source http://gems.github.com httparty river