Nexus One a revolutionary phone by Google and HTC is all set to replace iPhone 3GS! So following points make it clear that Nexus One will replace iPhone 3GS

*Talk time of Nexus one is 7 Hour(3G) and iPhone is 3Hour(3G)
*Nexus One is  capable of performing many tasks at a single time without disturbing performance.
*Nexus One is thinner than iPhone
* Nexus One comes with 5 megapixel camera and iPhone 3GS with 3 megapixel camera
*Qualcomm Snapdragon™ 3G QSD8250 chipset, delivering speeds up to 1GHz V/s iPhone's Samsung S5PC100 ARM Cortex-A8 833 MHz underclocked to 600 MHz PowerVR SGX GPU.
*Nexus One comes with  Battery 1400mAh  and iPhone with 1219mAh
*Nexus one has 3.7" display and iPhone has 3.5" display
*Nexus One currently has access to more than 18,000 applications and it is believed that number of applications to cross 100,000 by Q3 2010.
* Easy synchronization  with all Google applications. 
*Google is all set to launch many advanced features for its Nexus One Phone.

All these advanced features comes with a price tag of $529 that is $70 cheaper than iPhone(without Contract). With contract you can buy nexus one at $179.

HTC Google Nexus One Full Body Protection Kit by Phantom Skinz