Possible Duplicate:
Does Google App Engine support SSL for apps hosted as mydomain.com?
I know that GAE does not support this yet, but is there any reason it can't be done? If they can add support, I'd assume they're working on that. Have they said anything about this publicly?
SSL for custom domains is supported for tests since October 2011.
Update: Full description of SSL for a Custom Domain.
They can - there is no technical reason why not, especially with newer TLS versions (RFC 4366) which support virtual hosted SSL/TLS. Before this point an SSL session required a dedicated IP per certificate.
There are a few different ways they might choose to handle this, including automatic IP address re-routing and SNI. It has been one of the most requested features for well over a year, and very recently, they officially put it on their Product Roadmap. It was also mentioned in their App Engine for Business announcement.
You can run SSL on your custom domain by using a third-party service. Here's a HOWTO I wrote up explaining how to do it using CloudFlare:
http://blorn.com/post/20185054195/ssl-for-your-domain-on-google-app-engine
They found an interesting way around the one-cert-per-IP address. Since they register the certificates, they register each cert with 20+ domains on it. That way they multiplex 20 different domains on a single IP address.
At any rate, we use it at Voost and we're pretty happy with it.
App Engine has now launched SSL for Custom Domains. You can choose from either SNI or VIP based SSL. Wildcard and multi domain certificates are supported which allow you to use your certificates across multiple applications and domains.
There is no such support at the moment but it's noted in the roadmap for upcoming releases.