You still have to specify one, it doesn't seem CFMap has any way to work around the fact that it's now not required for using the v3 API. Probably not helped by the way they rushed out a hotfix in May just before API v2 was going to stop working (now extended until November 2013).
The workaround - don't use the cfmap tag. It's simple enough to write the JS yourself.
Also make sure you select for API v3 and not v2, but otherwise I think that should work?
I've logged the mandatory API key as a feature request in the bugbase. You might want to vote it up: https://bugbase.adobe.com/index.cfm?event=bug&id=3588783