I was a bit surprised that this app does indeed allow access without ads, it certainly wasn't something I was expecting. More motivation to purchase a PandoraOne account for those that can do so. TBH I was lothe to pay for an account because even with a 'Desktop' app, both Adobe Air and Flash are required and I've had bad luck with both in the past. I'd hate to drop the money and then still deal with the tech that I was trying to get away from.
I did spend some time this morning wandering around their FAQs and it seems it's not possible to 'donate' money without paying for services. This is especially upsetting as the fees that Pandora pays do go to artists (and recording companies.) Nor is it possible to 'gift' a paid account in some way.

So to non Pandora One users: please consider the consequences.