Anyone know what, if anything, this means for the rate limits on issuing certs on a given domain? That was the one thing that was stopping us from making SSL completely automatic on our customer's domains.
So I think it's actually essentially unlimited, you just can't request the exact same certificate more than 20 times per week
An extreme example would be DDNS providers like No-IP.
[ed to add:] Note that while you can just use example.com, or add alternate names, that would mean that a compromise of www1.example.com also compromised the key used for db1.example.com etc - which would largely defeat the purpose of splitting up different services across different vms/zones/machines in terms of security compartmentalization, because you'd only need one copy of the key to mitm all services.
(For some setups, where everything is a set of web apps/services, and TLS is terminated at the load-balancer/reverse proxy, this is a moot point -- but that's not always a good idea. See eg: how Google suddently rushed to encrypt their intranet after it turned out NSA had been happily snooping on everything from the "inside" via datacenter links that I assume were across rented "dark"/dedicated fiber).