Alleged replacement parts for the iPhone 5 have already popped up on a part supplier's website, despite the fact that the device hasn't yet been announced. However, if the parts are real—and by appearances, they seem to be—the next-generation iPhone will likely be more evolutionary than revolutionary.
TVC Mall, a Shenzhen-based electronic parts wholesaler, is already listing replacement camera module, battery, and audio jack cable parts for what is labeled as "iPhone 5." The parts have some superficial physical differences when compared against the iPhone 4, however. In particular, the battery has an ever-so-slightly higher 5.3Whr capacity. The camera module appears to have some slight cosmetic differences, though none that would reveal whether Apple is bumping the resolution to a rumored 8MP or sticking with the current 5MP. The audio jack cable seems the most physically different from existing parts for the iPhone 4, but those changes don't really tell us much.
iFixit CEO Kyle Wiens confirmed to MacRumors that the part numbers for the purported replacement parts were at least plausible, even if he couldn't verify their authenticity.
If these are indeed parts for an iPhone 5, it does suggest that the design won't be radically different from the existing iPhone 4. Some rumors have pointed to a completely different form factor for the next-gen iPhone, while others suggest a more conservative update with largely internal changes, similar to the iPhone 3GS.
The less radical approach is the one we believe Apple is most likely to take for this revision. We expect Apple will include an updated A5 processor in a form factor largely identical to the current iPhone 4. Other possible enhancements include the aforementioned camera resolution bump, dual-mode Qualcomm baseband, and NFC hardware, possibly for an iTunes-based mobile payment service. Since Apple's most recent hardware updates include support for the latest "low energy" Bluetooth 4.0 standard, we also believe support will show up in the iPhone as well.
The next-generation iPhone will likely be announced in September, perhaps as early as September 7.