Thanks to Keith Furman for the tip: Microsoft has quietly started seeding the mirror sites with Internet Explorer 5.0 Beta 2.
The setup initialization program (455 KB) can be downloaded from the Web. You then run this program to install IE 5.0. The new install program will allow you to install any of the IE 5.0 components you'd and it will even let you keep your old IE 4.0 browser (it's hidden in Customize installation then Advanced), which is kind of nice. Installation size ranges from 6 to 45 MB, depending on what you decide to update.
For more information about this build of IE 5.0, please visit WinInfo on the Web.
UPDATE: It appears that any mention of an IE 5.0 release is a bit premature: The IE5Setup.exe program mentioned above is apparently correct, but the available sites are all password protected and, no, I don't have a login for you to use. According to a confidential source, the sites that do appear during setup are there only for testing and Microsoft isn't quite ready to post the real thing (though the release is imminent).
What this all means, of course, is that IE 5.0 isn't quite ready yet. Sorry for jumping the gun, but I wanted to get that story out as quickly as possible because the weekend was coming but I see now that it was mistake.