It looks like this just became another option when pricing on continental.com.
In addition to the normal search criteria (full Y fare, Nonstop only etc),there are two new check boxes that read as follows:
-Eligible for OnePass Mileage Upgrades* (No V, Q, S, T or L Fare Classes)
-Eligible for Most OnePass Promotions** (No Q, S, T or L fare Classes)
It seemed to work for a couple of simple itineraries I priced out and I think this might actually be a nice, useful feature!
(Edited To Add

This is found using the advanced search option
[This message has been edited by OutOfOffice (edited 06-10-2003).]