VideoGaming247 and Gaming Age, have seemingly been told a few of the details by inside sources and the word is spreading like wildwire. Even Insomniac's James Stevenson popped up in the NeoGAF thread to lend credence to the rumor and Jason Dobson over at Joystiq has also confirmed the news via his sources. There's no official word, obviously, so you're going to have to take their word for it.
Firmware 2.40 will apparently include in-game XMB and 2D XMB trophies. If true, this may be the firmware update that shuts the fanboys up. As for when it's coming, no-one really knows. Though there is a rumor that it will be out pre-MGS4 in order for the game to take advantage of the trophy system. Now that one is a rumor, so don't be surprised to see MGS4's release come and go without any word on 2.40. We're hoping to see an announcement soon. If we find out anything more, we'll be sure to let you know.