According to Joystiq, since the PS3’s release, the memory footprint of the OS itself has dropped from 120MB to 50MB, which, in turn, has given developers 70MB more of RAM to work with in development. According to Patrick Seybold of SCEA, it has been done over time from the network updates:

Since the launch of the PS3, we have been continuously making efforts to reinforce our support system to game developers, allowing them to express their creativity freely on the PS3. As part of this support for game development, the size of the PS3 OS memory footprint has been reduced through network update for the game developers.

Though, it’s not enough to drastically change anything, it could result in better looking games in the way of dynamic lighting and effect resolutions, according to game developers. Like Joystiq says, it’s rare to see a spec upgrade in the middle of a console’s life!