Not sure if that's a good thing; guess, it depends on how much of a role each star will play.
Chris Hemsworth and director Kenneth Branagh were in Rome discussing the Thor movie.
Hemsworth was asked about Portman having a role in the Joss Whedon directed The Avengers, via BadTaste.it (love that movie, btw!).
The Thor movie star confirmed that she is (assuming my Italian is correct) in the movie.
Ci sarà anche Natalie Portman?
Hemsworth: “Sì, Natalie ci sarà”
Actually, I hit up Yahoo Babel Fish translator:
There will be also Natalie Portman?
Hemsworth: “Yes, Natalie will be”
I think from that, we can gather that Hemsworth is stating that Portman is in The Avengers.
The Avengers hits May 4th, 2012 and is directed by Joss Whedon, starring Robert Downey Jr. as Iron Man, Chris Hemsworth as Thor, Chris Evans as Captain America, Samuel L. Jackson as Nick Fury, Mark Ruffalo as the Hulk, Scarlett Johansson as the Black Widow and Jeremy Renner as Hawkeye.
Thor hammers into theaters May 6th 2011, directed by Kenneth Branagh starring Chris Hemsworth as Thor, Tom Hiddleston as Loki, Anthony Hopkins as Odin and Natalie Portman as Jane Foster.
If you can't wait for the movie, script spoilers have been leaked!
For even more, head on over to the Cosmic Book News Thor movie hub where you can find additional news, images and trailers.
Thor Trailer #2: