There's now a rather meaty thread on Mac Rumors' forums detailing problems that iPhone 4 users have had with miserably slow upload speeds in HSPA-equipped AT&T markets -- speeds that had in some cases been well over 1Mbps before the holiday weekend but have since fallen to 100kbps or lower. A popular theory is that AT&T decided to cap speeds in light of the iPhone 4's success and the danger it poses to network oversaturation, but we're not buying it -- 100kbps is ridiculously slow for an HSUPA-enabled network, even a heavily-used one, and there are huge markets (LA, for example) that seemingly aren't affected. We don't know what's going on, but we've reached
