All, There exists code in the sample console consumer that ships with kafka, that will remove consumer group id's from zookeeper, for the case where it's just a short-lived session using an auto-generated groupid. It's a bit of a hack, but it works (keeps the number of groupids from proliferating).
I'm wondering if there is a clean way to do this while using the new kafka offset storage. I didn't see an example of this in the latest console-consumer sample. Thanks, Jason