I did a specs comparison between the Samsung Galaxy S and iPhone 4 a few months ago: http://extorian.co.uk/blog/368/samsung-galaxy-s-versus-iphone-4/
All of my sources are linked from that article, and I believe there are a couple of minor errors that show the iPhone 4 to be better than it really is...
For example, you mentioned that the Nexus S and iPhone 4 use the same video solution (the PowerVR SGX540). This is true for all Samsung Galaxy S (including the Nexus S) phones, but the iPhone 4 uses the PowerVR SGX535. This actually makes quite a big difference, as the former has a performance of around 90 million triangles per second, while the SGX535 on the iPhone 4 can only put out 28 million triangles per second. So, the Nexus S graphics, like all Samsung Galaxy S phones, on paper is around 3x faster than the iPhone 4.
You mention that both the Nexus S and iPhone 4 have BlueTooth 3, but in fact the iPhone 4 only has version BlueTooth 2.1.
It might be worth mentioning that while the iPhone 4 does have marginally better battery life for talk time, this is highly dependant on signal strength, which the iPhone 4 suffers from greatly thanks to its well documented antenna problems. As such, in the same circumstances, the iPhone 4's radio uses far more power than the Nexus S radio and hence greatly shortens the iPhone 4s actual talktime. On paper the iPhone 4's talktime is better, but in practice it may well not be.
Finally, the battery section doesn't mention standby time, which is arguably the more important figure than talktime. The Nexus S has a standby time of 428 hours versus only 300 hours on the iPhone 4.
