Video Info:

Main Title	: Dragon Ball Kai
Genres	: Adventure, Aliens, Cyborgs, Fantasy, Genetic Modification, Humanoid, Martial Arts, Shounen, Space Travel, Super Power
Episodes	: TV Series, unknown number of episodes
Aired	: 05.04.2009 till ?
Reference :	AniDB

- The DBZ TV series is receiving an extensive "refresh" for Japanese television airing
- This is a celebration of the 20th anniversary of DBZ
- While based on the original animation production, it is being updated with new technology
- This includes cropping the frames for formatting on an HD 16:9 display
- The original Japanese cast is re-grouping to re-voice the show (where available, and unfortunately not including those that have passed on, such as Hirotaka Suzuoki [Tenshinhan])
- Sound effects are being updated
- Unlike the general show, the OPs and EDs are being completely redone
- While not in the above announcement, other reports are noting that the number of episodes is being reduced from 291 to approximately 100

New content:
- A brief look at the last moments of Bardock and Planet Vegeta
- An overview of young Goku's growing up years (Dragonball, the pre-Z period) up until his triumph over Piccolo at the Tenkaichi-Budokai.
- The all-too-brief and yet still somewhat triumphant return of FARMER WITH A SHOTGUN!

And sadly (although that really all depends on how you look at things...)
- Goku's winky has disappeared!

That's right, through the miracle of "we're just not gonna draw it anymore", Li'l Goku is no longer going to be allowed to show off "Even Littler Goku" on TV. But don't worry, they won't do anything so blatant as to digitize tighty-whiteys on him.

- The story will be developed speedily! -- "Kai" starts from the invasion of the Saiyans. This version will be re-edited to hew more closely to Akira Toriyama's original story, so the story's development will progress all the faster!
- The opening and ending songs will be completely renewed!! -- The opening and ending songs will together be made anew! Furthermore, in "Kai", the background music will be newly recorded. Let's enjoy "Kai", where even the music has been powered up!!
- Through digital processing, the image will be made vibrant!! -- All the grime, damage and noise remaining on the "Z" film will be removed! In HD, the image will be even clearer. We've carefully made the ultra-powerful "Kai" world even more impressive!
- An all-star voice cast will record the lines anew!! -- The original main cast, centered around Masako Nozawa as Son Goku, will reunite, yo. They'll breathe life into the characters again, to support their appeal!!

[taken from Daizenshuu EX]