> If IBM had loudly (and correctly) proclaimed that mainframes were the place to run web services, everyone and their mother would be running mainframes right now instead of Linux boxes.

No, they wouldn't. I could take one Linux box, get a domain name, and have a web server. I wouldn't be able to afford a mainframe, though. And if your alternative is renting a fraction of a mainframe, the answer is no. No, I will not trade a Linux box that I control for renting a piece of a mainframe that I don't control. Just no.