LTE has been turned on for Philly and Wilmington, DE. Even more excited to have the iPhone 5 this Friday. 
This is from DSL Reports.
On the heels of recent expansion earlier this month, AT&T today announced that the company has brought their shiny new LTE network to four new markets. According to the AT&T website, the carrier has launched LTE services in Albany and Rochester, New York, Philadelphia, Pennsylvania, and Wilmington, Delaware. According to AT&T's handy-dandy LTE infographic (pdf), the carrier has now launched LTE services in part or all of 65 markets, with plans to reach 100 before the end of the year, and all current HSPA+ markets upgraded to LTE by the end of 2013. The launch of the iPhone 5, as excpected, has drawn greater scrutiny to AT&T's LTE coverage or lack thereof, especially when compared to Verizon's (371 markets).
This is from DSL Reports.