I've been trying to confirm this with Microsoft all day and so far I haven't gotten a definitive answer back, but word on the street is that the final release version of IE 4.0 will be somewhat different from the version we've seen as Preview Release 2 (PR2). In PR2, the Web view and one-click, Web-like Explorer are enabled by default and, in general, most users seem to prefer it that way once they get used to it. Reports are circulating, however, that Microsoft plans to ship IE 4.0 with this feature disabled so that the Shell is unaffected when you install the browser. If you'd like to turn on the one-click Shell, you still can. Also making the rounds is a story stating that the base install of IE 4.0 (the "Standard" install) will include only the IE 4.0 browser and Active Desktop, not Outlook Express (email and news) and other IE 4.0 features. This is similar to Netscape's recent release of the standalone Navigator and Netcaster product.
I suspect we'll know by the end of the week whether this is true or not