As it clearly states on AA.com:
"Effective August 23, 2001, US Airways' participation in the AAdvantage program will end. AAdvantage miles may be accrued on US Airways Shuttle flights using the Shuttle Bonus Offer through August 23, 2000 as scheduled."
Hmmmm, maybe that isn't so clear. In any case, you can still earn 500 AA miles on US Air Shuttle flights until August 23. I'm really going to miss this program.