The title??!

I found the japanese word for Sennen Joyu

Then typed it into the below website

http://www.csse.monash.edu.au/~jwb/cgi-bin/wwwjdic.cgi?9T

and it came up with this:
(n) millennium; one thousand years; ED
(n) actress; (P); EP

So it seems to be correct!

The actual japanese text doesn't seem to work on this board

I'm pretty sure that her film roles were set anywhere from the 1500s to sometime in the future, probably around 2500. About 1000 years.

If you want to take the magic realism[1] elements of the story a bit literally, the "Millennium Actress" title refers to the Thousand-Year Tea. The following interpretation, it should be warned, turns the movie into a fantasy film, and this is not to everyone's liking:

During the Sengoku Period of Japanese history, there was a princess whose love was taken from her by an opposing army's forces. She happened to live in a haunted castle. The ghost of the castle, who'd been watching the princess all her life, and who'd grown to hate her and love her, tricked the princess into drinking a potion that trapped her soul in the wheel of reincarnation for a thousand years, constantly acting out the role of chasing after her love but never finding him. Taking this a bit further, the traditional assignment of roles would imply that the ghost is the princess's mother who died in childbirth and who feels jealous that her daughter lived, or, given her reappearance later (below), a caretaker or nanny who died at some point during the princess's childhood.

The princess also had a loyal samurai vassal, who promised to give his life to save his lady, and who entangled himself in the curse as a result. Also entangled is a vassal of the forces responsible for abducting the samurai lord. Finally, the ghost, too, is bound to the wheel of fate by this act, escaping entrapment in the castle for entrapment of another sort.

The movie takes place about 500 years into that thousand year curse, where the princess is incarnated as an actress in Japan named Chiyoko Fujiwara, the samurai vassal is incarnated as a younger film-assistant-turned-documentary-director named Genya Tachibana, her love is reincarnated as an anonymous anti-government painter, and the hostile samurai is incarnated as a policeman. By coincidence or fate (if there's a meaningful difference between those two concepts), many of her films recount the stories of her previous lives. During the life shown directly in the film, however, the curse is sort-of-broken, because Chiyoko Fujiwara realizes that it's not just a curse -- it's also a blessing. She enjoys her role and if she embraces it, her thousand years of chasing after her lost love can be a thousand years during which she she knows purpose and fulfillment, if not happiness. The curse is half a gift because the ghost both hated and loved her.

Taking this tack, the spaceship scene is a prophecy about one of her future lives, possibly the life where she finds her love beyond the trip through hyperspace but also possibly just one of the many lives where she chases after him.

I didn't see any of this until I realizes that old woman Chiyoko Fujiwara's maid (who first greets Genya Tachibana at the door) has the same face as the ghost (though this is not immediately apparent because the ghost's hair is stark white while the maid's hair is dull grey). The maid loves Chiyoko and takes care of her but also resents her, as her face makes plain in one of the scenes in the house.

All of this is pretty ridiculous, and it's not what the movie is about, but it's consistent with what's shown on the screen... except for not accounting for the recurring presence of Eiko Shimao, the older actress, but I'm sure I could come up with an explanation for that if I tried hard enough. At the very least, we can assume the life of the princess involved some character not unlike Eiko, even if she was never shown, and it would not be difficult to fabricate a reason why she'd be entangled in the curse along with the princess, the vassal, the opposing samurai, and the lord.

I don't see much of a problem in reconciling this interpretation with the more realistically satisfying "don't take the magic elements too seriously" interpretation. It can be both at the same time! I am unaware as to whether Satoshi Kon intended it, but since the movie and Satoshi Kon's body of work in general tends towards postmodern, and one of the tenets of postmodernism is the death of the author[2], I feel comfortable asserting its validity. (I will take this opportunity to point out the absurdity of bringing up the author's body of work as justification for invoking death of the author as an analytical tool.)

The above text is only half satire. Try to guess which half!

[1] http://en.wikipedia.org/wiki/Magic_realism
[2] http://en.wikipedia.org/wiki/Death_of_the_Author

Stephnls analysis notwithstanding...

The title is pretty straightforward. Literally, she is the 'Thousand year actress' since her roles span about 1000 years.

But more importantly, she is a 'once in a thousand years' actress. Her talent is so great, we might see this level once in a thousand years. The title is not only descriptive, it is praise for her talent.

This film is loosely (very loosely!) based on an actual Japanese actress named Setsuko Hara. She, too, became a recluse after retiring at the very top and at her peak of success. Hara is still alive; I think she's 91 years old. Sometime around the time this film was made, Hara was named Japan's greatest actress of the 20th century. 'Millenium Actress' alludes to that, only implying she's the best of the millenium, not merely the century!

If you want to see Setsuko Hara at her best, see Banshun (Late Spring) by the director Yasujiro Ozu. That, or Tokyo Monogatari (Tokyo Story). Many people consider either (or both) of those films to be among the greatest ever made, anywhere!

I look at it like this. The release of this film was 2001, so assuming it takes place in present day, it is the turn of a new millennium for an actress who who has been acting since childhood.