The Raspberry Pi 3 is still relying upon Broadcom's VideoCore IV, but its speed is bumped to 300MHz compared to 250MHz with the earlier RPi devices. While the same VideoCore IV tech is present, it's not quite out-of-the-box but there are some yet-to-be-merged patches needed against the VC4 DRM driver.
Once the Raspberry Pi 3 was announced this week, Broadcom's Eric Anholt who has been developing the VC4 Linux driver stack sent out the few patches needed to get the kernel driver working for the RPi3. There's just two patches needed, "These are for fixing the vc4 driver on the Pi 3. Note that patch 2 will also be necessary for fixing HPD on the Pi2, which we've been carrying downstream patches to work around until now."
That work should work its way into the upstream Linux kernel soon. It looks like my Raspberry Pi 3 will be arriving tomorrow so soon after will be able to start pushing out some performance benchmarks overall for this $35 ARMv8 development board.