Original: June 29, 2007
iPhone 3G: July 11, 2008
iPhone 3GS: June 19, 2009
iPhone 4: June 24, 2010
iPhone 4S: October 14, 2011
iPhone 5: September 21, 201
About every year. 15 months being the largest gap. If the "5S" comes out a year'ish from now, it wouldn't be a surprise.. I'm only interested in generation gaps (i.e., iPhone 4 to iPhone 5) The "S" line, if I may, has never offered anything worthwhile IMHO.. Siri was added in the 4S and to be honest, she isn't all that helpful.. Why would you hold down the home button, wait for Siri, ask it about the weather, wait for the question to be sent via cellular data, and then a response sent back via cellular data, when you could slide to unlock and drag down from the top in .5 seconds?
Here's the problem.. Too many people want the "exclusivity" of the "latest and greatest".. They would rather spend $600 out of contract to get a phone with a talking voice when they had a perfectly adequate iPhone 4. Doesn't make much sense to me..