They're shooting themselves in the foot with this policy IMHO. Business users especially aren't going to put up with a constant changing major version number, it just generates too much support problems. Plus, then you end up with stupid systems like one we have to deal with that hard code in checks for browser numbers, and heck, that one's not working with FF 4 yet, or IE 9. (Yeah, I know, you can make the browser claim it's the older version, and then it works with this system, but that's not something I'm going to try setting up for all my users, I have real problems to deal with.)