According to a trusted source (via Engadget), new iPhones in 4GB, 8GB, 16GB and 32GB capacities have just received approval from the PCS Type Review Certification Board. This board is responsible for handset certification for wireless carriers including AT&T. That would indicate the next generation iPhone could come out in four models. If this proves to be true, it's not clear if Apple will utilize iPhone OS 3.0 to differentiate capabilities between the models. Just days way from Apple's WWDC and possibly four new iPhones.