Lee has announced he doesn’t want to travel to New Zealand if he is featured in the hobbit. This note appeared from Cinematical:

Lee isn’t interested in filming in New Zealand again because it is simply too far away, for too long of a time. You can hear the tiredness in his voice — and perhaps a bit of regret too.
That doesn’t mean Lee isn’t interested in being in The Hobbit at all, however! He’ll appear in the film as long as he can stay in London, and there’s a character he’s quite keen to play. Or rather, voice.

The voice he wants to play, you may have guessed, is of Smaug.

This interview found at Rushprint had Lee speaking about the Return of the King, not returning to New Zealand and his offer to play the voice Smaug.

So now we have the infamous Count Dracula, Darth Tyrannus, Saruman planning to do the voice of smaug.