But the basic functionality of ICS is the notification bar dropdown in basic lockscreen mode. Did you see the YouTube video yet? I was on the phone for over 2.5 hours with T-Mobile and Samsung yesterday. So I hope this gets fixed soon. I was told even before I got the GS2 that all functions of ICS (from T-Mobile representative) it will be on the GS2. Even the Samsung tech rep was surprised to find out this was not on even on his test (tmo) phones. So I hope this helps all with the GS2.
I watched the link that you posted, that video showed the basic lock screen mode (small lock icon) swipe it out to the side to unlock: dropdown notification bar must work even in lock mode.
But if you choose to lock it with pattern, password, pin number or face unlock that dropdown notification will not function unless in unlock mode.
Android 4.03 (ICS) is an optional software update for GS2 T-mobile: read this
Samsung company released the ICS software update for international version of GS2
T mobile tech tested and modify it to be fuctional to the T-mobile GS2 (used a qualcomm chips) and its HSPA+4G
AT&T have their own version to work on their GS2 ( used Exynos Chips) and its 4GLTE
If you have time kindly read this