These certs have now re-appeared on Delta.com with an issue date of 1/28/10 and an expiration date of 12/31/10. You can't redeem them online, but you can view them.

Go to the redeem multiple certificates page, check the "View Certificates and eCredits by Certificate Number" box, and enter the e-cert number or numbers (starting with 012) in the appropriate spaces. Click "Continue" and you should see your certificate information along with a link to view the T&Cs.

They now say:
"Eligible on Delta, Northwest, ASA, Comair, Delta Shuttle, Chautauqua, Compass, Freedom, Mesaba, Pinnacle, Shuttle America, and SkyWest only. Regional carriers are subject to change. Miles off Award Travel certificate is Valid for one round-trip First-Class or Coach-Class ticket on published routings within the 48 contiguous United States and Alaska or between the 48 contiguous United States, Alaska or Canada to Mexico or the Caribbean."

No more NW metal only restriction (which obviously makes sense).