Something looks awfully familiar in these screenshots (1, 2) in the version of IE that will supposedly ship with the next Windows (codenamed "Longhorn"). This after a build of Longhorn was leaked to the public.

So it seems they finally decided to institute a popup blocker. And emulate Mozilla extensions with their IE Addons. Hmm... This is good news in the sense that Mozilla had it right all along.

Source: Longhorn PDC Build 4051 Leaked