I somehow didn't hear about this until just now.... but t-mobile, using MS cloud computing, lost the servers with the data of all their sidekick users. Sidekick users store their data, such as phone #'s, pretty much everything on this cloud system, so losing it, and it being unrecoverable, is a massive mistake.
http://www.engadget.com/2009/10/10/t-mobil...-data/#comments