This one is currently not feasible, but worth keeping an eye on in case the fees come down.

www.brawker.com

7% "discount" for bitcoin buyer (that is passed to the CC buyer) is the deal killer here, as well as the relative "newness" of the service.

Works like this:
Person A wants to buy something online with bitcoin from a site that doesn't take bitcoin.
Person B wants bitcoin.
Person B uses CC to buy item for Person A, and Person A then "pays back" Person B in bitcoin.
Brawker acts as an intermediary to make sure no one gets the shaft.

Person B in this scenario is the MS-er, and would immediately turn the bitcoin back into dollars using another platform (like Coinbase) to avoid price fluctuation risk.