Probably is. But you will have to go to a GM/Saab dealership the last I heard.
If you went to a Saab only dealership it may be useless so depending on where you live, you are covered at one, but may not be at a Saab only. Simply, there was no mechanism for a Saab only place to bill GM since the COP was under GM. They were working on something and that (Saab only), issue may solved so call if getting to a "joint GM/former Saab place is a problem. My bud bought his 08 from a dealer just before the collapse but another dealer (Perrine Buick/GMC) has been doing his CPO and he has been quite relieved.
Remember, there is also a powertrain warranty on our cars and a dealer can tell you when it expires, it's not as extensive as the "CPO" and is not bumper to bumper so your radio is not covered.
Basically cars built under GM such as my 08 and Wifey's 09 as is your 08, are fine, it was cars built after the saale Victor Muller and Antonov (Saab-Spyker or a few other names they went by), are the ones without coverage unless they bought it from a private insurer.
I think the coverage on my drivetrain expired last week on my (the 2008) car.
I have an 07 Aero sedan that I purchase in Nov. 99 with a CPO warranty. Last month I had an ABS sensor, brake master cylinder, and some other stuff replaced under warranty. The work was done by a former Saab dealer who is now a Fiat dealer.