Thanks to all our Chicago readers who sent in their speed test data from their iPhone 3G and 3GS. Here's our conclusion: the 7.2Mbps AT&T's testing in Chicago doesn't really make any difference right now in speeds.
The 3GS turned out to be slightly faster in downloads (1202kbps vs. 1161kbps), but just about the same in uploads. Its latency was much better 175ms vs. 210ms, which reflects the same thing we found in our iPhone 3GS review and is probably attributable to its faster processor.
Either AT&T's 7.2Mbps isn't really widely deployed yet even in Chicago, a city they've been running deployment tests on for a few months now, or it makes no real difference in everyday usage. We'll test this again once 7.2Mbps gets rolled out to more cities to find out which.
And if you're still not sure about what 3G speeds mean, or the differences between different phone techs, see our Giz explainer on all the mobile terms. And the next generation technology? 4G? See what's coming up in that explainer. [Thanks to all our readers who participated!]
Update: AT&T tells us that the trial is only live in Chicago on a handful of cell sites and on an internal basis, so none of you guys should be connecting to the faster network. The public trials are coming later this year, so it makes sense that the speeds are exactly the same.