WillFletch,
I think you would be surprised how many are compatible, the better question is how many are not compatible! However, there are a few considerations you could make in your build in regards to the GTX 570:
1) Does your case have the clearance for the card? - this a problem that most of us have ran into more often than not.
2) The GTX 570 uses PCI-X 2.0, as mentioned above almost every modern board for a gaming build ranging from cheap to expensive will likely support this card.
3) Make sure power supply can push the card (500-550 Watt minimum) and have room to expand if you want to use SLi (750-800 Watt minimum), such as have multiple 6/8 pin power connections for the card.
4) If you want to expand to more than one GTX 570, your new mobo will need to be SLi ready, so this will typically be an Intel/Nvidia type setup.
If I'm telling you things you already know I apologize, anyways, hopefully that is helpful.
If you are looking for more specifics in your board, just let me know and I could try to make some recommendations