I believe the 'portpass' is for land access only; if the program is still functioning.
For flyers, there was a pass available called
INSPASS. This died after 11/9.
There is some dated information here:
Frequent Traveler? Apply for INSPASS.
Currently a replacement facility termed CBP-PASS is under investigation. Here is a
1.8Mb .pdf with some more information:
Securing the Frontline, U.S. Customs and Border Protection, 2005–2010 Strategic Plan