How everything started, and what it is:

The name "Expanded Universe" makes reference to expand a current universe. In this case were talking about the universe George Lucas created a long time ago. So it means that every content charged to expand the content of the movies IS and WERE considered as the "Expanded Universe" which was into the lucasfilm canon. So, the first content that expanded the universe was showed in Marvel comics' magazine Pizzazz with a series of comics called "The Keeper's World" it was produced since 1977 to 1978. In 1978 we got "Splinter Of The Mind's Eye" which is the first Expanded Universe novel. In its introduction George Lucas Said:

" After Star Wars was released, it became apparent that my story was only one of thousands that could be told about the characters who inhabit its galaxy. But these were not stories that I was destined to tell. Instead, they would spring from the imagination of other writers, inspired by the glimpse of a galaxy that Star Wars provided. Today, it is an amazing, if unexpected, legacy of Star Wars that so many gifted writers are contributing new stories to the Saga."

George Lucas in an interview with a TotalFilm interviewer, on the May 2008 edition of TotalFilm Magazine:

TotalFilm: How far down the line will Star Wars continue in these new incarnations?

Lucas: Clone Wars will probably go for at least five or six seasons which adds up to 200 episodes. Then we have the live-action series, which is going to be a little bit more experimental. It takes place over the 20 years when Luke's growing up, but it's not about the Skywalkers or any of that stuff.

Like In Episode IV -- you hear about the Emperor, but you don't actually see him. People live in the Empire, but you don't see Storm Troopers. It's a completely different kind of idea, which is risky. But that's the only reason I'm doing it. Some people will inevitably say. "It's not what I think of as Star Wars." So who knows, it may work or it may not.

TotalFilm: Is it really a radical departure?

Lucas: I'd say so. It's kind of like Episode IV -- it's funny and there's action, but it's lot more talky. It's more of what I would call a soap opera with a bunch of personal dramas in it. It's not really based on action-adventure films from the '30s -- it's actually more based on film noir movies from the '40's!

TotalFilm: Any casting news?

Lucas: No, that won't be for a while. We've got writers who are currently working on scripts with the art department. First you've got to create the characters, because half of them are human and half of them aren't.

That's the thing about Star Wars -- there's always two and half years of design work before the production stars. Nobody spends that long in television; people have a tendency to just put t-shirts on actors and call them spacesuits! Or they just use motorcycle helmets and paint them green or something. So we've been working on this for about a year now: designing sets, environments, vehicles and aliens...

TotalFilm: The Star Wars universe has expanded far beyond the movies. How much leeway do the game makers and novel writers have?

Lucas: They have their own kind of world. There's three pillars of Star Wars. I'll probably get in trouble for this but it's OK!

There's three pillars: the father, the son and the holy ghost. I'm the father, Howard Roffman [president of Lucas Licensing] is the son and the holy ghost is the fans, this kind of ethereal world of people coming up with all kinds of different ideas and histories. Now these three different pillars don't always match, but the movies and TV shows are all under my control and they are consistent with themselves.

Howard tries to be consistent but sometimes he goes off on tangents and it's hard to hold him back. He once said to me that there are two Star Trek universes: there's the TV show and then there's all the spin-offs. He said that these were completely different and didn't have anything to do with each other. So I said, "OK, go ahead."

In the early days I told them that they couldn't do anything about how Darth Vader was born, for obvious reasons but otherwise I pretty much let them do whatever they wanted. They created this whole amazing universe that goes on for millions of years!"

TotalFilm: Are you happy for new Star Wars tales to be told after your gone?

Lucas: I've left pretty explicit instructions for there not to be any more features. There will definitely be no Episodes VII - IX. That's because there isn't any story. I mean, I never thought of anything! And now there are novels about the events after Episode IV, which isn't at all what I would have done with it.

The Star Wars story is really the tragedy of Darth Vader. That is the story. Once Vader dies, he doesn't come back to life, The Emperor doesn't get cloned and Luke doesn't get married...

So, George lucas licensed and approved and was so involved in the expanded universe. But he never consider a grand amount of it as his canon (which is the the movies from 1 to 6, the clone wars movie and the clone wars tv series with the unfinnished storyreels) BUT any content that george lucas took from the expanded universe and then put it into the movies or TCW were automatically George lucas' canon.

Some examples:

kashyyyk (name)

Twi'lek species

Couruscant (name)

Datapads (yes that one from the phamtom menace in which shmi watches anakin in the pod race)

Aayla Secura

501st Legion

Anakin's scar (George was tol to put the scar in revenge of the sith to explained later in other source, and he accepted.)

And the list does'nt end here, there are a lot more but i wanted to highlight some of them.