Sorry I have been so silent as of late. I have had a bit of
information for a bit, but I have been waiting for confirmation
(lest Dan Hollis and Ryo-oh-ki jump all over me). 
Most of this information I got from a fan in Japan. The April
Anime Rags (B-club/AX/Dragon and Aniamge) also have quite a few
tidbits...In addition, I got my hands on a copy of True Tenchi 3.
My friend is translating it for me (the same who translate the
above stuff), so I hope to have a summary in a day or three..


These are from the rags:

Here are the tidbits:

- Haruna (TMiL2) will be "someone familar" Dragon actually hints
that it is one of the Tenchi girls who is "Linked to the Tree"
(sasami?) 

- Nagi will have a small cameo in the movie. 

- The Gaurdians will have "a definite role" in the new flik. Nobuyuki
will not. 

- "Negishi: All though Tenchi has been a family so far, we decided to
make this movie on what would ever happen if he were to pick a girl" 

- "This will be sad Tenchi Muyo" 


But then came the great bit... There has been some discussion of late
about Kajishima, since there has been some confliting reports on when
a OVA series will be made..... In True Tenchi Three there is is a statement

"There will be the third (and final) Tenchi Muyo OVA story next year."

And the end of the book is a section titled in english "Tenchi Muyo New
Secrets"

here are the tidbits:

- There will be two new Tenchi girls (My friend is not sure about
the Kanji, but it looks like "Minako" and "Mysterious Girl". 

- All of the Tenchi Characters designs will change. (I will
try and scan these when I get a chance). 
- Aeka moves to her blue haired design...
- Washu looks more adult. 
- Ryouko looses about 1/2 her hair. Still spikey on one side, but close
cut on the other. (They, for some reason, have a two designs for 
Ryouko, the second looks like a combination of Ryouko and Washu, ie, the eyes 
are wider, and she has Washu's front of hair design. 

Sasami looks even older. Even freakier, there are three designs of Sasami,
each at a different age. One ala her current design, one as a teen ager (15sai0
one as Tsunami). 

- Najya Akara will show up. (sidebar: "One day Tenchi comes into bathroom
and runs into Kagato. Then he discovers Kagato has breasts. It is Najya
who looks exactly like Kagato with sleepware")

- Mihoshi's bro (He is the blonde bishonene from the artboook). 
 will show up w/ a GP strike team. They arrest tenchi, but Washu blows up
 their ship in orbit, leakving them stranded!

- I have heard rumours that one of the things that is keeping the OVA
series back is Yokohama Chisa (Nadesico: Ruri's Voyage) and Orikasa Ai
(SMJ JtoX) availability. I have also heard that for some reason they
only need Ai for one episode. 

- A strage girl will show up who can generate LHW, but won't tell
tenchi who she is. 
 
- Opening song "Unknown Love" sung by Megumi Hayashibara. 

There was a nice little blurb at the end of TT3:

"Origionally Tenchi was going to be love story. But we kept introducing
new females, so tenchi had to be ataru. Origionall tenchi was going
to be in love with (16sai) Sasami. So instead we picked family. Tenchi
will never pick girl, otherwise Ryouko and Aeka would kill him.
...


Anyways, more scans as I get a chance....