Wow, a few months back my co-workers and I actually came up with the same idea. Pretty cool. We never figured out a good solution to actually redeeming your beer though. Getting local bars onboard just seems a bit too difficult.
We also make an assumption that the person is on an mobile phone with recent webkit browser for redemption. We're going to work on an iPhone and Android app once the rumble is finished.
I'm hoping the having the secret codes for the bartender to input works well.