Since you can charge an iPhone when near a power outlet, car, or USB port, I don't really have much of a problem. I don't go all out playing these games on here, which means less than 30 minutes whenever I do. Most of the time it's more like 15 minutes when doing something like waiting for a doctor. Scrabble runs the battery down, but it's not like flooring a V8 engine in first gear for 10 minutes. It still does fine considering you're taxing the resources.
I haven't looked at this for iPhones, but I know Energizer and others made portable battery packs to use on either iPods or cell phones. You just plug them into the right port. If someone hasn't done this for iPhones, they're missing out on huge bank.