Looks like the first unofficial scene for The Avengers was shot for - Thor!
In an interview with Empire, Stellan Skarsgard, who played scientist Erik Selvig in Thor, informed us that Joss Whedon actually directed the post-credit scene for Thor (spoiler below the video). Whedon is directing the upcoming Avengers, Kenneth Branagh directed Thor.
Skarsgard stated he flew over and did the quick scene with Samuel L. Jackson and then flew back.
He was also asked about where his character was going, with the actor replying that he couldn't say anything.
Check it out:
Selvig is shown walking side by side Nick Fury, with Fury revealing to him a cosmic cube (tesseract) - with Loki shown manipulating Selvig.
Thanks to Comic Book Movie for the cool find!
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.