Nick Carr has an interesting post about Sun’s new data-center-in-a-container, or trailer park computing, as he calls it. (Sun calls it the Blackbox.) If you have power and electricity, here are up to 245 servers (presumably, Suns running Solaris) and you can have computing on demand in a very literal sense.
I think this is less important as a product than as a physical prototype for services yet to come. There aren’t that many companies that need rent-a-centers for shorter periods, and those who do can probably do much with dynamic server sharing or perhaps farming some of it off to offerings such as Amazon’s S3 service. But the thinking that went into the configuration and customer interface for the computing container will represent a very significant step on the way to IT as utility, delivered through sockets in the wall (or, for that matter, wirelessly.) What is available in hardware will be emulated in software, eventually.
Update: Bob Cringely has some good comments and the history of how Sun was started. He thinks there is a market for a couple hundred of these boxes, Sneakernet fashion.