Recently, two of the movie's writers said in an interview that there was a scene written for him originally. Ultimately, though, their idea didn't feel "organic" enough and they didn't end up using it.
Now that I've seen the movie I still can't decide if including Shatner would have been a good idea or not. On one hand, it's a nice nod to older fans and could have been an easy passing-of-the-torch gesture. On the other hand, if a scene doesn't work it doesn't work, and making a good movie was obviously the top priority for Abrams and his team.
What do you think? Should the new Star Trek filmmakers have found a way to include Shatner?