From http://support.microsoft.com/default.aspx?scid=kb;[LN];834489:

Excerpt:

SUMMARY

Microsoft plans to release a software update that removes support for handling user names and passwords in HTTP and HTTP with Secure Sockets Layer (SSL) or HTTPS URLs in Microsoft Internet Explorer. The following URL syntax is no longer supported in Internet Explorer or Windows Explorer after you install this software update:

http(s)://username:password@server/resource.ext

Good going guys, considering this is officially in the HTTP specification.

Oh well, it wasn’t the first, and I doubt it will be the last.