[Update: 12:26 PM]: EA just confirmed to me that while there is in fact a WWII level in the game, "we're not discussing any details about it right now." Kind of saw that one coming.
The ESRB has once again revealed some rather intriguing information on a high profile game by way of their always informative rating summaries. This time, the game in question is DICE’s upcoming Battlefield: Bad Company 2, and the noteworthy piece of info is that the game actually features a section that takes place in World War II.
As the ESRB notes, "In single-player mode, players conduct missions on an unnamed Japanese island during World War II and then move into the modern day through jungles, deserts, and snowy terrain."
From the sound of it, the game opens in the past, perhaps establishing either a character or plot connection with the modern-day battling that serves as the basis for the rest of the game. I contacted EA to see what they might be willing to reveal about the section/sections, so I'll let you know if hear anything.