iFixit

The Qualcomm MDM6600 chip supports HSPA+ data rates of up to 14.4 Mbps and CDMA2000® 1xEV-DO Rev. A/Rev. B

You can view the datasheet for more information on the chip.

This is the same chipset as the Droid Pro world phone. It supports both GSM and CDMA—which means that Apple could have supported GSM!

Why didn't they? It may be that it was easier to design antennas for a CDMA-only phone -- this phone supports two cellular frequency bands, while Apple supports five bands in the GSM version.

Of course, there's no way it could be a real "world phone" without a SIM card slot.