Through his Twitter page today the iconic Stan Lee confirmed that he will in fact make a cameo in Kenneth Branagh's Thor. Here are some selected offering's from Lee himself:

Can't tweet anymore. Due to Thor, I must start rehearsing my thee's and thou's. So, if thou objecteth not, I wish thee well! 'Nuff saideth
Of course, my previous tweet revealed the extent of my innate modesty. I really wanted to add "With me doing a cameo, Thor's a sure winner"
Yeah, I mentioned Ken Banagh a few times, but I warned you I was a name driopper. Seriously tho', with him directing, Thor's a sure winner
went easy on Ken Branagh when we discussed my role in Thor. Told him I wouldn't insist on my name above the title, I think he was grateful

The production is about to start casting.

Marvel Studios expands its film universe with a new type of superhero: Thor. This epic adventure spans the Marvel Universe; from present day Earth to the realm of Asgard. At the center of the story is The Mighty Thor, a powerful but arrogant warrior whose reckless actions reignite an ancient war. Thor is cast down to Earth and forced to live among humans as punishment. Once here, Thor learns what it takes to be a true hero when the most dangerous villain of his world sends the darkest forces of Asgard to invade Earth.

Thor stars Chris Hemsworth, Tom Hiddleston, Natalie Portman, Anthony Hopkins, Jaimie Alexander, Colm Feore, Samuel L. Jackson, Stellan Skarsgard, Stuart Townsend, Ray Stevenson, Tadanobu Asano, Idris Elba and Kat Dennings.

Thor comes to theaters May 20, 2011 from Paramount Pictures and Marvel Studios.