While at Interop, I managed to stop by the FORE Systems suite in the hotel across the street. It was impressive. They claim to have customers with their WS adapter cards.
Standard disclaimer applies.
They said that the applications were not modified to run over the ATM interface. No elaboration on the IP over ATM scheme being used. Their WS adapter cards are based on AAL3. Looks like you would have to toss these and buy new ones when the ATM Forum AAL5 based UNI gets finished. No CPU on the adapter cards.