Actor Timothy Spall who plays Peter Pettigrew talked about what his character is going to be up to:
Moviehole talked to ”Sweeney Todd”’s Timothy Spall who confirmed he’ll be back as Peter Pettigrew in another ”Harry Potter”.
“Well I’m actually…. yes… I’m in the next one”, reveals the British actor. ”And I’m also in the one at the end – I have a very big scene in that. I think they might be shooting two of them back-to-back – hard to know though, what with this writer’s strike and all. They’re shooting the penultimate one at the moment – which I have a brief appearance in it. I should be doing that soon.”
Spall appeared as Peter Pettigrew in ”Harry Potter and the Goblet of Fire” and ”Harry Potter and the Prisoner of Azkaban”.
– source

He’s actually a great actor.
He was in a new Oliver Twist series a while back as Fagin!
=]