On the subject of Dragonball Kai, it's really nothing to get excited about. I've seen the first couple episodes and essentially it's a rerun of Dragonball Z. The opening and ending may look nice and shiny new but the in-show animation is still old with the same sub par 80s Toei Animation, it's not updated and tells the same story as Z. If you want to see Dragonball Z remastered with better sound and forced into widescreen, it's already available here on DVD from Funimation on the current season sets. I couldn't really justify continuing to watch it personally, but give it a shot if you want.When will that be hitting the US, dubbed, in Blu-Ray?
Well, I think the appeal of Kai is going to be the removal of the filler that accumulated in the show. These first few episodes won't be much different because the show was still very tight. But, I wouldn't be surprised if the episodes with Vegeta and Nappa will be much more succinct. Though, maybe not.
The real difference will definitely shine when it comes to the the Frieza fight. I imagine it'll be like night and day.
Oh come on - it's NOT DBZ unless you have 22 minutes of dialog like:
Vegeta: "I'm going to have to power up and use my super-sayian ultra attack..."
Goku: "Oh no, he's powering up and using his super-sayian ultra attack..."
Announcer: "Can Goku counter Vegeta's super-sayian ultra attack?"
Vegeta: "I'm almost there, no one can counter my super-sayian ultra attack..."
Goku: "Oh no, he's almost ready! I don't know if I can handle his super-sayian ultra attack..."
Announcer: "Next time on Dragon Ball Z CAN Goku counter Vegeta's super-sayian ultra attack?"

All 200+ episodes seem to follow the above rule, you could skip a week and not really miss a thing.