Because the iPhone 4 has support for High Speed Uplink Packet Access (HSUPA), it can reach upload speeds up to 5.76 Mbps. On the other hand the iPhone 3Gs is lacking support for HSUPA, and it is limited to just 384 kbps..
AppleInsider notes that in the USA, AT&T’s 3G HSUPA network operates with typical speeds ranging from 0.5 to 1.2 Mbps. Other countries with better more established 3G networks could see greater speeds.
