I have a Dell Latitude D620 which is a Centrino Duo with a i9xx chipset and a sata disk using libata and Fedora Core 6. The machine suspends and resumes fine when there isn't a HDD password set. Our corporate laptop usage policy requires all laptops to have a HDD password set. When a HDD password is set the machine suspends fine but on resume it doesn't properly come back. X comes up with a blank screen and if you switch to a console it just starts spewing libata disk errors. It should initially display the BIOS screen and prompt for the password. It did this fine on my old laptop which was a Dell Latitude D600 running Fedora Core 5. I've never run FC5 on this laptop, nor FC6 on the old one so not sure if its due to move from PATA/ide to SATA/libata or a kernel bug or something else.
Seems to be fixed in Fedora 7 + recent updates.