The DIA (no, not the Defense Intelligence Agency) is a global trade and research organization with its US headquarters located in Horsham. DIA stands for Drug Information Association (not to be confused with the DEA-Drug Enforcement Agency), although it usually refers to itself just by its initials. The DIA says it "is a nonprofit, member, and volunteer-driven association that provides knowledge resources across the full spectrum of medical product development".
It will hold its annual meeting, DIA 2012, kicking off today at the Pennsylvania Convention Center, and continuing through the 28th. The DIA tells me it expects 7,000 attendees, 550 exhibitors, and 895 speakers.
The DIA is a big event for many Philly area companies in the Clinical IT side of the business, such as Octagon Research Solutions, NextDocs, BioClinica, and numerous others. The meeting on the whole is very scientific and quite expensive, although there are plans for individual days or specific sessions (still expensive). I think there are more affordable Exhibit Hall-only options available, although I haven't been able to confirm the specifics on those.