The Zi6 is clearly inspired by the Flip Video, and has a form factor similar to that family of devices. The main advantages of the Zi6 are that it can record at 720p HD resolution at up to 60fps, has a bigger screen, and the native video file format is H.264, so it's Mac compatible out of the box. The Zi6 also has a fixed macro mode, which it appears the Flip does not.720p HD at up to 60fps! That is really quite something for such a small form factor.
I have a flip video ultra and love it for what it is. The zoom is basically worthless, but for recording some small video clip it is worth every penny. I basically use the flip video camera like a point-and-shoot camera the way I would compare my canon hv20 HD camcorder to my canon DSLR's. Quick and dirty verses slow but better.
Amazon has the Kodak Zi6 for $180 and you can compare that to the Flip Ultra for $120.
I have to say even though I have never maxed out my flip yet, I would think the ability to use the expandable SD memory card in the Kodak alone is worth the extra 60 bucks. Anyone out there tried one of these Zi6's yet? What did you think?