PS2 Maybe downgraded in graphics, but they are getting extras...

"Ubi Soft has announced that it will be adding a number of new features to the PlayStation 2 version of Splinter Cell. The game will feature an all-new binocular-vision headset, four new levels in the power plant area, 30 additional minutes of cinematics, and a new four-minute intro with music performed by the Prague Orchestra. Ubi Soft also has plans for Tom Clancy's Splinter Cell to support Dolby Pro Logic II sound.:

Although I do imagine that all of these features will be available for download on Xbox Live.