@Ian
But that is what cloud computing is about: No need to set up your own servers, no need to put up the infrastructure recommended beyond the servers themselves (server room, redundant power / internet connection, admins to pay) and moreover: no need to pay up front. If your web2.0 CRM idea you hosted on force.com fails, you will have lost only the time you invested and maybe a few bucks you paid for extra service.... If on the other hand customers think your app is the best thing since sliced bread, than you will also have no problem scaling up by using the massive salesforce infrastructure, which could be a problem if you are doing your own hosting.
On the other hand, the additional convenience of course has to be paid for. Whether this is really worth it is an individual trade-off, of course.