[biff]

Note, I'm not saying it's a fantastic idea, just something that happened to occur to me as a possible development in Bitcoin's future.

It'd likely be along the lines of anti-spam lists. You might have one that's high-profile thefts or seizures. For that matter, these lists could be political, issue-based, or whatever.

It's ridiculous and unlikely to be followed if taken out to the extremes of issue-based disputes, but I don't think it's impossible for a significant number of people to agree not to transact in stolen Bitcoins, some on principle, some as self-preservation (the exchanges), and most because their utility is reduced by the first two groups refusing them. This also happens to increase the value of untainted Bitcoins.