FUD Zilla spotted someP55 motherboards with display outputs and CeBIT and heard it's still uncertain whether the P55 chipset will support processors with integrated graphics.
For the consumer this isn't a huge issue right now, just stay away from any P55 motherboards that has display connectors on them, as they won't work with the first generation of CPUs, as these CPUs don't have integrated graphics. As for the motherboard manufacturers, well, time will tell, but the current designs might not work once the CPUs with IGP becomes available in early 2010.
The H57 and H55 are sure bets to work with the CPUs that have integrated graphics as they will be designed for the new CPUs. This might cause a lot of confusion for some consumers and the upgrade paths are anything but clear. For now it seems like you might have to swap your board every time you buy a new CPU, which will make upgrading more costly than it has been recently. Then again, a lot of people just buy a new system these days, so maybe this isn't a huge issue for most.