Paul Bettany will be voicing artificial intelligence yet again for the Marvel universe.
The addition makes sense, considering Ultron's involvement. The evil machine built Vision to help him defeat the Avengers, but Vision broke his programming and ended up helping the super team beat Ultron.
Currently, the big rumor about The Avengers' story is JARVIS becoming Ultron somehow. It was assumed if this was true, Bettany would voice Ultron (that job went to James Spader instead). It would make sense that The Vision could be recognized as the "good" part left of JARVIS if he had Bettany's voice.
The Vision first appeared in 1968 and has been a part of The Avengers team for decades. Although he was destroyed at one point, he was rebuilt by Tony Stark - offering another plausible entry point for the hero. Either way, expect more than one android blowing things up when the highly-anticipated Avengers: Age of Ultron hits theaters in 2015.