i know there's something similar going on at the valley forge convention center also. it's not just audio though, it sounds like it's going to be basically anything and everything under the sun. supposedly from all of the companies going out of business in the area. i think that's going to be where tweeter has most of their out of business sale stuff.
here's some stuff i found about the Ft Washington Expo Center:
http://www.phillyblog.com/philly/bur...expo-sold.html
http://www.socialweb.net/Places/4178.lasso
Seems it did actually disappear. haha. if i were you i'd probably plan on making the trip to the valley forge one instead if you still want to get some deals.