If you take the example quoted by Amazon, a medium sized website db of 100GB and averaging 100 I/Os a second over the course of the month, it would cost $26 a month to host it in the cloud. There are SQL Server AMIs already available - I haven't had a chance to use them yet - been working mostly with Oracle AMIs so far.

I think it's a great concept. It's going back to the old timesharing days when you'd log on to an IBM mainframe and pay for what you used.