The problem has since been fixed, but that's not really the problem. The problem is that Google offered little to no support over the weekend, costing developers their valuable revenues. Many of those affected developers are now asking Google for refunds on the transactions, claiming that Google is responsible for their lost income.
We've now heard that Google was still receiving their 30% cut, even when the developers were seeing "Payment declined" messages. That alone might be argument enough for developers to get at least some of the revenue they lost over the weekend.
A Google representative said that they "regret the inconvenience and pain caused to all of you, and take our responsibility to our merchants and developers very seriously." They have made no mention of potential compensation. Both Google and Microsoft are going to have to work harder to keep their developers happy. In an app-driven mobile market, their satisfaction is just as important as the end-user's.
source: Android and Me via Electricpig