Marvel would, it seems, like to give the Hulk another big screen solo effort… eventually. Such a film, and Mark Ruffalo starring in it, are certainly being talked about now even if there is (almost) nothing definite about it.
Marvel Studios' Kevin Feige had a talk with EW, and said that while a script is not currently being written, there is some discussion about what storylines might be part of such a film. Most notably, a "Planet Hulk" tale appears to be out. Feige denied the rumor about a "Planet Hulk" movie and stated "What we're excited about exploring and expanding is Mark – and Banner's not in 'Planet Hulk' at all."
The next big question is when we could actually see a Hulk movie, and the basic answer there seems to be not for a long while. Feige is quoted as saying "We're excited to sit down and go, 'What is a stand-alone Hulk movie?'" Which seems to mean that they haven't actually had that conversation yet (except apparently enough to know that they want to do something but it won't be "Planet Hulk").
The big green guy hasn't done brilliantly in his first two solo big screen efforts, 2003's "Hulk" with Eric Bana as Banner and Ed Norton's 2008 turn in "The Incredible Hulk." Reception to Ruffalo's portrayal of the character in "The Avengers" was far more positive and it is interesting to think about what a stand-alone effort featuring the actor would look like, even if it is years away.
Is a Hulk movie on your list of wants for Phase 3?