As noted by ThisIsMyNext, a prototype iPhone 4 appeared on eBay this weekend. This prototype iPhone 4 has many of the signs that it is a pre-release device. The volume buttons don't have the + and - markings as the production models have, and the FCC ID, Size and Model numbers are X'd out on the back casing. The eBay description details the findings:
1. iPhone has wear on the frame, some small marks on the rear cover, small marks on the screen. No cracks and no deep scratches.The iPhone 4 prototype is notable for being one of the most leaked Apple devices ever. A prototype of the device was said to be found in a bar, after which it was sold to gadget blog Gizmodo. The site then did a tear down and analysis of the device well before its launch.
2. Volume buttons don't have the usual + for upper button and - for lower volume button
3. Phone will not activate on at&t and when syncing with iTunes it says that this phone can not be activated with at&t sim card it won't activate (please review picture #10)
4. On rear cover Model No.: XXXXX FCC ID: BCGAXXXXX IC ID: 579C-AXXXXX (please review picture #8)
5. Front screen and rear cover has some type of numbers printed on the inside.
Update: As is frequently the case with Apple prototypes appearing on eBay, the auction has been shut down.