(Copying this from a post on Daizenshuu EX.)
(From Shonen Jump)
Translation:
20th anniversary of Dragon Ball Z!
The legend of Z will be back with the newest digital technology!!
Starts at 9:00AM in April 5th 2009, on Fuji TV!!
1. More exciting by re-editing!!: The footage will be totally re-edited and HD-remastered!!
2. New opening and ending!!: Both footage and songs will be renewed! The sound effects in the show will also be renewed!!
2. Superb seiyus will gather for the show!!: The show will be re-dubbed by the original casts!!
They'll be reconstructing the 291 episode series to about 100 episodes, to update the old animation, fix the errors, sound effects and even the music and Opening/closing themes. This is for the 20th Anniversary of the sequel to Dragon Ball.
And this is from an update on the main Daizex homepage:
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 extending the frames for formatting on an HD 16:9 display (note: not cropping the image)
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
This begins 05 April 2009 @ 9 am
This means the filler scenes will be completely gone and inconsistencies will be completely fixed, like Vegeta's Orange and Lime flavoured Armour. And no more Garlic Jr. or any other painful filler.