I've been looking for a way to do this for a while (obviously didn't look too hard) and this works really well for me. My goal is to get all my disks "backed up" and encoded so that my AppleTV can play them from my NAS box with an AC3 soundtrack.
I have a Mac Pro with 2 DVD drives in it.
Opening 2 terminal windows allows me to make 2 ISO's at the same time, by specifying the different drive in each window. The hard disk is faster than the two DVD drives, so there doesn't appear to be a bottleneck, even when they are both being written to the same disk or folder.
The crucial piece, and if like me you just want the main feature, not the menus etc...is to use Handbrake as mentioned, but if you have VLC sitting in your Applications folder, the latest version of Handbrake uses VLC on-the-fly to bypass the disk protection.
My solution is now to RIP 2 disks at once and when they are done, queue them up in Handbrake to change them to my preferred video profile. I reckon I will be saving hours and hours by the time I have been through my collection!
Thanks again for the inspiration found here!