Wirelessly posted (iPhone 3G (white): Mozilla/5.0 (iPhone; U; CPU iPhone OS 3_0 like Mac OS X; en-us) AppleWebKit/528.18 (KHTML, like Gecko) Version/4.0 Mobile/7A341 Safari/528.16)
Actually, I never export directly from iMovie for two reasons. One, the quality is AWFUL. Second, I want two versions - one for my AppleTV and one for the iPhone. Since my source is always 720p AVCHD, I export to AIC without changing the resolution. I then send the exported .mov file through VisualHub - once for AppleTV and once for iPhone - using two-pass encoding. There is a HUGE difference in quality, not to mention vibrance/saturation. After that, I import both clips to iMovie, change the media type to "TV Show" and name each of them accordingly ("Family" and "Family HD", for example) ... When I sync my iPhone and AppleTV, I select the appropriate TV Show (SD/HD) and each device gets videos encoded specifically for it, at the highest quality possible. 🙂
As for the iPhone 3GS: since my wife and I both have our own phones, it would be GREAT if we could easily sync each other's videos back to both our phones. Since Apple's syncing method is rather convoluted, we can't do that. So for me, the workaround will be to sync the phones with iPhoto, export the movies from both devices that I want to keep on both devices, export the files, import to iTunes, change the media type to TV Show, and then sync that TV show to each device. In other words, it will require constant attention. 🙁