Cory has a great post titled: Scrum-ban | Lean Software Engineering. In it he describes how a team can take advantage of kanban within a Scrum environment.
While I am sure that there will be those who insist that Scrum doesn't need to be improved, there are those of us who learned Scrum, practiced Scrum and are aware of it's limitations and want our teams to get even better.
Personally I like kanban for the context I work in. When I explain how we develop software I always try to make sure the other person is aware of the context I made my decisions in and how in other contexts I would not make the same decision.
For instance we do not estimate each individual story (although for a short period we did 30 second estimating). We have collected enough data about our performance that we know how many stories per month we complete (~10). Part of this context is a stable team that knows the software and a mature product.
Back in the day I lead contract teams doing work for state and local government. In that context I would go back to estimating because the contracts tended to be fixed price and the team was pulled together just before the project started. Different context, different practices.