A Slack bot that publishes a team's pull requests to their Slack Channel (github.com)

Nice idea. Did you consider developing it as a plugin for hubot[0], or since you're working with ruby, then maybe lita[1], or ruboty[2] ?

I think it will take some of the heavy-lifting away, and easier to add for people who already use one of those robot frameworks (instead of running a whole instance just for one feature).

[0] https://hubot.github.com/ [1] https://www.lita.io/ [2] https://github.com/r7kamura/ruboty