While we'd love to drop IE6 completely, it feels crazy to do so while it's still 20% of visits. But there is definitely a lot of extra development time needed to keep things working for older browsers.
In both cases, we'd make it 100% clear why they saw more ads and paid more, with instructions on how to upgrade.
If everyone did such a thing, maybe we'd see the financial/annoyance incentive lead them in the right direction to browsers that don't cost as much to support.
It's been a long week, so this may be a bit crazy, but I thought I'd get some discussion going as Friday comes to a close.