James Gunn, Zoe Saldana and Dave Bautista are currently in Singapore promoting Guardians of the Galaxy.
In the following video we hear not only James Gunn talk about Guardians being possibly the start of more Marvel Cosmic movies, but he mentions that Joss Whedon had a hand in casting Thanos.
It's been rumored that Josh Brolin will play the Mad Titan Thanos, who was first seen in The Avengers movie, which hasn't been officially confirmed just yet.
Gunn says that because Thanos plays a part in his movie as well as Joss Whedon's, that they had to work together to cast Thanos.
Joss and I have been friends for a long time. Joss read the script and gave me notes on the script. And the biggest note he gave was to make it more "James Gunn." And I said, "It's you're funeral." And that's what I did.
So that was Joss' input basically. We also had to work together in casting Thanos because Thanos is going to appear in stuff that I do as well as stuff Joss does. Other than that, I pretty much had free reign.
James Gunn also previously mentioned that Guardians of the Galaxy ties into The Avengers 3, and it's also been said Thanos will be featured in The Avengers 2, with it speculated to all be leading to The Avengers 3.
Guardians of the Galaxy hits August 1st.