[Rewritten by BL 7/15/07] So far, software king of free DVD ripping, Handbrake, has yet to come out with an iPhone preset, but the iPod one works fine. And remember that Handbrake works on copy protected discs, too.
Roxio's crunch is good for non-DVD, video to iPhone conversion and like Handbrake, it does export for most other devices, too. This software costs about $30. Works pretty well. It claims to handle discs, but like most commercial products, won't rip anything copy protected, making this part of the package useless. Best part of Crunch? Fast batch processing of many files.
Visualhub, another paid piece of video ripping software is getting rave reviews, although I've never used it. Most attractively, you can use xgrid to do your compression across multiple networked Macs. Bad ass.