In its effort to get users onto IE8, Microsoft might end up alienating its intended audience instead. For starters, Microsoft pushed out IE8 as a critical security patch via AutoUpdate, which caused some users to install the browser when they didn't want it. Plus, the standard settings make IE8 the default browser, as has been Microsoft's custom, so some users not only ended up with a browser they didn't want, that browser became their default.
Then come the issues with IE8 Beta 2 and Windows XP SP3. A Microsoft blog posting about installing IE8 contains a warning that it is possible for users of IE8 Beta 1 and SP3 to get locked into IE8 and SP3 with no ability to uninstall. The only way to avoid the lock-in is to uninstall both IE8 and SP3, then re-install SP3 and install the latest IE8 build.
[ In terms of browser share, IE's overall numbers are dropping as Chrome, Firefox, and Safari pick up steam. ]
Of course, you'd have to know to do that beforehand, and Microsoft's decision to push out IE8 as a critical fix through AutoUpdate can deny people who aren't fully plugged-in with the latest IE developments -- which would be most users -- the opportunity to avoid the IE8/SP3 lock-in. By doing what they're told to do, i.e. keep their software updated and patched, users could find themselves stuck.