I dont know why this is a shock to anyone.

iPhone release dates:

Oirginal iPhone - June 2007
iPhone 3G - July 2008
iPhone 3GS - June 2009
iPhone 4 - June 2010
iPhone 4S - October 2011

iPhone 5 - summer 2012?

Why is anyone surprised another model is coming a year down the road since iPhone 4S?