Someone called Joe Maddalone seems to have found out how to run more than one version of Internet Explorer side by side on the same Windows Machine without setting up different partitions.
If this turns out to be true, then it should greatly benefit Web Development since we should be able to test out designs in IE6 as well as IE5/IE5.5 without having multiple partitions.
Update: No one seems to be addressing what the consequence will be when Microsoft issues one of their patches.
A few questions I would like to see answered: what happens when the next Cummulative Update for Internet Explorer comes around? What gets patched?
I haven't actually tested this new development out, but I assume these old browsers still connect to the internet, therefore, if you are going to try it, please remember that running IE5/IE5.5 along with IE6 is for web development only, it is for testing your designs in a safe environment and these old Unpatched browsers must not be left unattended on the Internet.