But even if you don't want or need multiple OSes, vserver installs a RHEL 6 kernel. And it works with CentOS 5. Say you need ATA TRIM? You got it. Having trouble getting WiFi working? Bingo. Card reader on your Laptop not working? It does now.
EDIT: the catch is that sound is no longer working. While this is OK for the laptop, it isn't for my desktop. Ah well.
However, I can TRIM corey's SSD by booting with the vserver kernel, then doing
dd if=/dev/zero of=/tmp/very-largeThe first command is going to fill any remaining space on the disk with zeros, so don't be doing anything important at the same time. When the disk fills up, it will exit and the second command will free the space.
You could also do the same thing with any boot CD that has TRIM support.