If you are targeted, you can use the following link to take advantage of this promotion:
membershiprewards.com/pwpco20
Again, this is only for Pay with Points intineraries booked through the AMEX website from 06/15/10-08/22/10, not for Onepass transfers.
Normally, points are used at a ratio of 100 points: $1. With the promotion, it's only 80 points for every dollar in credit.