Two answers:
1) To support SPDY, the HTTP/HTTPS load balancers must support NPN negotiation as part of the SSL handshake. I don't believe the existing LB's have support for this, hence you won't be able to use the platform LB's.
2) If you configure the load balancers as simple TCP proxies, and push the SSL negotiation down to your app servers, then you can deploy an app server which can perform NPN negotiation (for example, Apache with mod_spdy, or node-spdy, etc).
Same strategy applies for AWS as well.