A few more additional tidbits:
I believe Tim Curry IS interested in going to London to do SPAMALOT.
As for Mary Poppins, it will come to Broadway but it will get re-configured (lightened up) for Broadway. The show is way too dark and the show will try to address the issues brough up by the less than favorable reviews by the Ben Brantley and Michael Billington (who's the "dean" of London theatre reviewers).
"It does what a musical is supposed to do; it takes you to another world. And it gives you a little tune to carry in your head. Something to take you away from the dreary horrors of the real world. A little something for when you're feeling blue. You know?"