*checks tags* Three. '03, '04, '05. Clarifying, Tekko is Pittsburgh's local con. '06 will be at the Expo-Mart in Monroeville, like last year, and the dates are
March 31 - April 2.
If you need eastern PA, there's another smallish con in Philadelphia in the spring. *googles*
Kosaikon.
I don't think there's anything in central PA. And I mean... anything, not just cons.

/obligatoryjoke