I could swear I've seen this posted here already, but I can't find the thread. Anyway, if you scroll down a bit on that page, it says:
Carrier: AT&T (GSM based), T-Mobile, and Other GSM carriers*
* Please check compatibility with your service provider
Technology: 3G EURO Standard, Quad Band 850/900/1800/1900
It's a GSM phone, so in the US that means basically AT&T and T-Mobile (as is stated). If you aren't in the US, then I believe it should still work on your local GSM carrier. Someone feel free to correct any wrong information.
EDIT: Also worth noting is that this is still a preorder with no ETA. Something tells me that this GSM version won't be out for quite a while after the Sprint version. Paying $700 to preorder a phone with no ETA sounds like a poor life choice to me ;-) Also seems funny that it still has WiMax 4g support even though it would be activated on a GSM network, and as far as I know, Sprint is the only cell company that uses this technology. I'd stay away from it