The iPhone 5 is rumored to get an 8MP camera. Believing rumors in the supply chain, this is confirmed.
The current iPhone has a 5MP camera. Rumors about the iPhone 5 aka iPhone 4S are since day one mention a 8MP camera. That is not a surprise as most new smartphones adopt now 8MP camera sensors.
To even add more arguments for the 8MP camera upgrade in the 2011 iPhone take the latest rumor from Digitimes. Tawain's Largan Precision is rumored to see strong order for the 8MP lens modules from Apple.
Besides the A5 CPU upgrade the 8MP camera upgrade are sure things for the new iPhone expected in September. The A5 Apple CPU is already in the iPad 2. Everything else is still very much in flux. There could be an edge-to-edge screen, dual-mode (GSM and CDMA), smaller and thinner form factor and NFC.