The source reports that Karl Urban had been in talks to play Creed, but that talks have fallen out, opening the way for Butler to come in. While both Butler and Urban are fine actors, either of whom would work well for the part, one has to wonder why Tyler Mane, who played Sabretooth in Bryan Singer's X-Men hasn't been considered for the role.
The same source also suggests that director Gavin Hood has been courting Natalie Portman for the role of "Kayla." No details on the role are currently available.
Meanwhile, CHUD also reports that Deadpool may be appearing in X-Men Origins: Wolverine. The film received a re-write immediately before the WGA strike began, so details on the script remain uncertain, but we do know that the film covers Wolverine's early life, including his involvement with the Weapon X program, headed by William Stryker.
If this remains the case, it makes sense for Sabretooth and Deadpool, both of whom were involved in the project in the comics, to appear. David Goyer has long been rumored to be working on a Deadpool movie, possibly with Ryan Reynolds set to play the "Merc with a mouth", so having the character make an appearance in X-Men Origins: Wolverine would be a good way to set that film up.