Apple's yearly developer conference should see iOS 8, OS X 10.10, and likely some hardware.
iPhone 4 is Faster than 3GS and Slower than iPad in Early Benchmarks
iPhone 4 results on left, 3GS on right
Early benchmarks of the iPhone 4 show it to be 31% faster than the iPhone 3GS according to the Geekbench 2 app. Geek Bench has been a popular benchmarking utility on the Mac that has recently made the jump over to the iPhone. As always, benchmarks are a bit of an artificial gauge of performance, but can be useful in head to head comparisons.
The iPhone 4 is known to use the same Apple A4 processor that is also found in the iPad, but Apple has never revealed the processor speed of the iPhone 4. The iPad is known to have a 1GHz processor. We looked at a few benchmarking utilities to see if we could determine if the iPhone 4's A4 processor was the same speed as the iPad's. Unfortunately, the state of benchmarking on iOS seems a bit primitive, and is further complicated by the fact that iOS 4.0 does not run on the iPad. GeekBench, for example, only runs on iOS 4, so we can't compare it directly to the iPhone 4's results. A couple of other benchmarking tools available produced some inconsistent results, so we can't be completely confident in them, but it appears that the iPhone 4 is indeed faster than the iPhone 3GS but slower than the iPad.
BenchTest: 3GS: 2.298, iPhone 4: 2.514, iPad: 3.667 - This benchmark only showed a small increase in speed with the iPhone 4, but some of the results seemed strange. All the "seconds" in the iPhone 4 results were listed at 0.00, though a score was still generated. It's hard to say if the results are entirely accurate.
Checkup: 3GS, iPhone 4, iPad - This also showed the trend of iPad > iPhone 4 > iPhone 3GS, but running the benchmark multiple times could result in a large variance.