As you know, the iPhone 3GS is a UMTS/HSDPA (850, 1900, 2100 MHz) device that also operates on GSM/EDGE (850, 900, 1800, 1900 MHz) bands. According to the FCC filing of the Nexus One, it is too a quad-band GSM/GPRS/EDGE with UMTS/HSUPA handset that also supports HSPA 900 / 1700 / 2100 and quadband EDGE.This doesn't surprise us as tt has also been rumored that Nexus One will be sold unlocked which means it can operate on a number of networks like AT&T and T-Mobile.
Just like the iPhone 3GS, Nexus One will also support , 802.11b/g WiFi, and Bluetooth 2.1 + EDR. When it comes to cameras, the Nexus One has an advantage since it may have a 5MP camera as opposed to iPhone's 3MP camera. The Nexus One is also rumored to have a 3.7-inch AMOLED display which is slightly bigger than the iPhone's 3.5-inch. Also, Nexus One has microSD expansion slot.
Since very little is known about the Google Phone, we cannot bring you a full comparison but the Nexus One's biggest advantage may be that it will ship unlocked. Keep watching this space for updates on this fascinating device.