AT&T has announced details of its upgrade pricing scheme for the iPhone 4. According to the company, new customers, upgrade eligible customers, as well as any iPhone customer who would be upgrade eligible for a discounted device by the end of 2010 will be able to purchase the iPhone 4 at the $199 and $299 price points with a new two-year agreement. AT&T customers can instantly check their upgrade eligibility dates by calling *639# from their…
