What makes a Star Wars universe feature "official"? My fan-dom has never gone beyond sincere admiration of the original movies (never read the books or played the games). But having made that disclaimer, in my mind, nothing is official unless it comes straight from George Lucas, at least as long as he is alive and still producing material.
Nick was more accurate to say that these Forms are "Expanded Universe", and I'm not sure how "canon" these are as to people really get into hugh debates as to what is and is not canon in the Star Wars Universe. But they are part and parcel of the LucasFilm Licensing and therefore has George Lucas' stamp of approval. That to me is enough to be "official".
"Official" I believe that it is something sanctioned by George Lucas. I believe if it has a LucasFilm seal on it then he has technically approved it. There are the movies (Ep. 1-6) and then there is the "Expanded Universe". Expanded Universe material are those materials that fall outside the movies which include books, comics (graphic novels), cartoons (i.e. the Clone Wars series on Cartoon Network), video games. If you really want to get into some debates on that matter check our www.theforce.net
Go to their forums (Jedi Council Discussion Boards).
Regarding the Lightsabe Forms, if you go to the link that Nick provided you will find a reference to "Forms" there are seven in all and have names, too. They are more like "Styles" than katas and are used depending on the circumstances. One would use Form I against multiple opponents and Form VII against another Force user (one on one combat) with a lightsaber but not against multiple users because a Jedi is then vulnerable to other attacks while too busy focusing his/ her use of The Force. The seven Forms outlined in KOTOR:II -- The Sith Lords (which is a Lucas Arts Video game)(which has essentially adapted the Forms spelled out in the Star Wars Insider Magazine) are:
Shii-Cho (Form I)
Makashi (Form 2)
Soresu (Form 3)
Ataru (Form 4)
Shien (Form 5)
Niman (Form 6)
Juyo (Form 7)
The game itself describes each form but if you go to the above link you'll get a good description, too.
It's my understanding that the First Form is supposed to be the most equivalent to how we practice martial arts. BUT, all the other "Forms" are based on one's mastery of "The Force", which of course does not exist in our real world lives -- only found within the fantasy of the Star Wars Universe.
It's my understanding that Mark Hamill trained in Kendo before filming Empire and in the Prequel films the stunt coordinator (Nick Guillard?) has stated that he has taken from different martial arts to get a feel for different styles. Apparently, Count Dooku's style was supposed be modeled after fencing, Darth Maul had a big wushu influence thanks to Ray Parks. I believe in the next film, if you saw the Ep. III trailer we will get see Force vs. Force fighting (Anakin v. Obi-wan) and not just your traditional japanese sword fighting.