Good news: It looks like Sidekick data fiasco is finally coming to an end. Over on T-Mobile's Sidekick forums, an official Microsoft statement confirms "most, if not all, customer data" will return "as soon as possible", starting with personal contacts.
The statement goes on to say they will "work around the clock to restore data to all affected users, including calendar, notes, tasks, photographs and high scores, as quickly as possible."
The data loss was apparently caused by a system failure that created data loss in the core database and the back-up. I'm not sure if that means sabotage or not.