Here's my anecdote: My Prius was 12 years old with 136k miles when the battery died. This was a few months after buying my Volt and the Prius sat quite a bit. It was also the day after taking it on a ~150 mile trip to get snow tires put on, but that's probably just bad luck.
I did notice (in hindsight) that the battery seemed to drain especially quick going uphill on that trip. The car lived most of its life in El Paso, TX, so all that heat probably didn't help. I don't think driving it more would have kept the battery from dying, but it probably would have helped it last a few more months (at least allowing me to make use of the snow tires...).
I would say a 15-20 minute drive every week or two would be better than just having it idle for 30 minutes. Driving would help keep everything else in shape, too.