Microsoft wants you to have IE7 as soon as it's released later this year -- and that means ASAP. The browser is set to be added to Windows Update automatic installations, along with OS security patches and other updates. This is the first time Redmond has used the automatic distribution method for its browser (we'd note that Firefox already auto-updates itself, but of course it's not tied to the operating system as closely as IE).
Most users will download IE7 without much fuss, but developers worry that a premature installation will cause big interoperability problems with Web apps and sites -- an ongoing challenge that is complicated every time a browser update is released. Microsoft has helpfully made available a blocker toolkit for those folks, but is urging customers to take advantage of the security features in IE7.