The article at http://govindgsr.wordpress.com/ (you can find the video link in the article)challenges the sanctity of whole Vista Operating System. The author is doing some nail bitting tasks like:
(1) logs-in a User through Run As Administrator option.
(2) forces a User to have Dual Identity.
(3) logs-in a User in the Invisible mode. (The remarkable aspect about this Invisible User is that , Its a Super User which is logged in silently within the Standard(Limited) User account and almost every security Feature/Policy of VISTA FAILS to get applied here. This Invisible Ghost User has got the Full Unrestricted access to the whole System. It can perform any operation without any barrier(i.e.Neither UAC pops up nor anything stopping it) and without any notification to the operating system.)
(4) logs-in a 2 Users in one session. More than 2 users can also be Logged-in into the same session.
(5) forces 2 users login & working together in a Standalone System at a time. More than 2 users can also be Logged-in a Standalone System.
(6) compels dual Sign-on of a User.(User Login-in twice without Logoff/shutdown etc..)
(7) compels the Same User to have a dual set of privileges.
(8) forces permanently Shut-down of UAC without editing/changing the security/system policies.
(9) forces the UAC to have a dual behavior.

I am very much interested in knowing what microsoft is doing about this issue.

Video is located at Youtube and you can find the link in the article (link given above):