swsusp appears to properly hibernate a system, even if the root filesystem is on RAID 1. However, it will not resume to the same after reboot. The boot gives the message that appears in the first attachment. The boot continues after some moments, complaining that the RAID array is damaged and needs correction; no such problem occurs when rebooting off non-RAID root filesystem. Also, these scenarios are not affected by the modification of boot arguments; I found that I could either specify the resume filesystem or not in either case with the same results in either case.
I successfully re-created both the non-RAID and RAID1 scenarios of CentOS 5.5 hibernate/resume using VirtualBox 4.0.4 running on a CentOS 5.5 Host system, not to be confused with 2 distinct CentOS 5.5 VM guests running on that same host. This is repeatable.