[cmorrisrsg]

A viable solution going forward is to have browsers implement both the vendor-prefixed and non-vendor-prefixed versions of a property, but use the vendor-prefixed one preferentially. That would allow developers to use one non-prefixed rule in the common case where all supporting browsers implement the rule in the same way, but developers can target particular browsers if they deviate. Or if you're worried about the standard deviating, support vendor-rule and x-rule at the same time.

For the current webkit- mess, it's probably best to just have the vendors implement each others prefixes on a case-by-case basis (when you know the semantics are the same). There are way fewer browser vendors than there are website developers, and it's much easier to get them all in a room to agree on something.