We had deployed an update last night which apparently affected one of our web servers. So for the past 12 hours some of our users (half) experienced slow response times (>2 seconds). We think all transactions were complete if people had patience.
The ironic part is that this is one of the steps we are taking over the next month or two to improve the scalability of our site so it can handle 50,000 registrations in 10 minutes with everyone happy.
Also note that Amazon will be doing a rolling database upgrade the week of November 5. We are set up with redundancy in multiple zones so there should be no impact on RunSignUp users. If there is, the impact will be for 3 minutes. We will monitor and report as part of our efforts to be transparent on availability of our service.