I wish I knew where there was a schedule. I go to ESPN each trip (four this past year alone!), and the first and only time something has been going on was this past May. There was a panel doing a radio talk show in the main room, and we were seated to the left of the stage. The only person I recognized was Darryl Talley, who played for the Bills in the 90s (sigh, the glory years). I don't think anyone would have recognized him if they weren't from Buffalo, though.
I wish I could be of help with the schedule. The only thing I can think of is to go to ESPNRadio.com and check the schedule. If it doesn't say whether anything is being taped from WDW, maybe try emailing them directly through the website (I'm sure they would try to get you some answers).
I read somewhere that no more "athletes" will be at the ESPN Club. They still will have the shows but no guests. I got that info from espnnet.com but the site is under construction now. I know they still have a rasio show and a baseball/football show. I really liked popping in and seeing thefamous athletes but I guess it is now more. Hope this helps