Article I cought on Sound&Vision web site (sorry for the copy&paste):
"Eklund also told the assembled technical editors at the briefing that the first Sony Blu-ray discs will have an Easter egg for the serious videophile or technician: high-def test patterns hidden on the disc that, in the right hands, can be helpful for tuning or assessing HDTV image quality. Here's a hint: from a disc's main menu, use the numeric keys on your Blu-ray player's remote to enter the four-letter name of a famous electronics brand, just as you might on your phone. The menu of test patterns should appear."
Hmm... Can anyone spell SONY? DUH! :)