Users in a significant number of markets are complaining that they're suddenly seeing their upstream iPhone speeds capped at just 100 kbps (if that, some users report closer to 50 kbps). Given AT&T's 2008 HSUPA upgrades, those speeds should be at least 800 kbps. There appears to be no rhyme or reason to the speed issues -- with consumers from NYC to Orlando reporting problems -- but other users (like in Dallas) seeing nothing unusual. While it's possible that AT&T throttled upstream service in many markets to help manage congestion during the holiday weekend, a technical problem seems more likely given the severity of these problems. We've dropped a line to AT&T for an explanation.