The new Nvidia graphics in Apple's latest notebooks will heavily come into play with Snow Leopard, which will leverage GPUs for parallel processing. But Apple might have already uncorked some of that GPU power: A bunch of MacRumors readers are reporting that the new MacBooks might use GPU acceleration to tear through h.264 video decoding, greatly reducing the strain on the CPU.
They noted this apparent GPU acceleration when playing back 1080p trailers from Apple's site, which saw CPU utilisation drop from 100 percent in previous gen MacBook Pros to just 28 percent in current MacBooks, even though the CPU is the same speed and the Pro has more RAM (new MacBooks have a faster FSB, but it wouldn't account for this kind of bump). Nvidia cards do have hardware support for video decoding, so this would make sense, but Apple hasn't used it before.
The other possibility that MacRumors floats is that these changes could be based on improvements slotted for Snow Leopard, namely Quicktime X, "which optimises support for modern audio and video formats resulting in extremely efficient media playback." Apple hasn't confirmed this, so if you've got one of the new MacBooks and old one to compare, check it out and let us know how it looks. [MacRumors]