It is very often that zoom.it is not available. I have a few sites using zoom.it deep zoom image, so they all became unworkable, when zoom.it fails.
What is the problem?
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I cannot say that I share your experience of zoom.it not functioning, however I believe that it is a service running in Windows Azure and I did see on Mary Jo Foley's blog at ZDNet earlier today that Windows Azure had some problems in the last day or so.
Perhaps that explains why you were having problems earlier?