I received this email from Amazon a week or so back:

You are receiving this email because you registered with Amazon Mechanical Turk as a Requester with an address outside of the United States. We regret to inform you that Amazon Mechanical Turk will no longer support international Requester accounts starting October 1, 2007. On this date your Requester account will be closed.

A real shame, as we had a couple of interesting projects we were thinking might be a good fit with it over the last few months. But also a bit of a wake-up call: the lesson here is that unless a provider of APIs is going to commit to an SLA, or even their future availability, then it's probably foolish to rely on them. A semantic web of collaborating services is a lofty goal, but we'll still need commitments (probably underpinned by commercial relationships) to realise it.