Wirelessly posted (Palm Treo 650: BlackBerry9630/4.7.1.40 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/105)
In the airport, there is pretty much nothing landside except for that newsstand in Intl Arrivals. I would be very surprised if they sold SIM cards. If you are taking the SEPTA train into Philly, you will find a Verizon Wireless shop in 30th St Station.