Route 53 developer here. That's on our roadmap, but in the mean time there is this; https://code.google.com/p/route53d/

Nice. Any idea if "internal" zones (private DNS for my VPC) will be supported by route53 at any point?

No kidding. I love the local speeds, and no doubt Google and Amazon do a good job of redundancy, but I'm sure as hell not going to put all my eggs in one basket. Not with DNS.

I had the same problem earlier this year, and if Rackspace or Route53 had AXFR support, I would have used them in a heartbeat...

axfr support might be useful even if you end up using them as primary:

1. migration

2. standard "config" API. You just keep up using your scripts to generate/update bind/tinydns configs.