This thread is intended to keep track of all the apps that support Passbook. I'll add what I can see in the US store as of right now. As you notice new apps get added, please post them here!
American Airlines
Fandango
Live Nation
Lufthansa
MLB.com AT Bat
MLB.com At the Ballpark
Sephora to Go
Target
Ticketmaster
United Airlines
Walgreens
American Airlines
Fandango
Live Nation
Lufthansa
MLB.com AT Bat
MLB.com At the Ballpark
Sephora to Go
Target
Ticketmaster
United Airlines
Walgreens