Installing iOS 4 on my iPhone 3G made me think back to when I upgraded to Windows XP in 2001. The computer was top of the line when I bought it just 2 years prior, but XP was a total dog on it.

However, a 2 year old PC would run Windows 7 just fine when it came out. It seems like there was a tipping point where PCs became overpowered relative to what most people ask of them. As a result they have more staying power in the face of software updates.

It doesn't look like we've hit that point with smartphones yet, but I wonder when we will...