The company hasn't explained the surprise cutoff, and we've reached out to get more details -- does this affect Xbox users, for example? However, it may simply be a matter of getting a solid return on investment. Bitcoin is still something of a niche payment method despite its increasing legitimacy, and some of its long-term supporters are losing faith. Microsoft may have decided that there weren't enough people buying with virtual cash to justify maintaining the necessary code.

Update: Microsoft now says that FAQ update was in error, so your Bitcoin should still work in the Windows Store.