I went through automated border controls in Helsinki, Finland in Sep. 2012. I have a German passport including biometry data. I did not need any special registration.
The procedure is as follows: The machine scans your passport. After that, you have to step inside and look into a camera. If the machine recognizes you, you are let through. That's it.
As far as I can tell, it seems to really be the case that they only use biometry information stored alongside the photograph.
I was actually quite delighted when I went through them. Zero waiting time!
In HEL they allow EU, EEA, Switzerland and Japan passports, see their website. There does not seem to be a registration. (More details from the Finish Border Guard)
In FRA they allow EU and Switzerland passports, though apparently you do have to register now. Source.
The site also mentions they use an iris scan to identify you. In 2011 I went through automated border control here, but my experience then was the same as in Helsinki in 2012 and did not involve registration or iris scanning.