According to this wiki http://www.liferay.com/community/wiki/-/wiki/Main/Portal+Atom+Collections in Liferay 6.1 it's suppposed to be
I know that for axis webservices the URL has changed from 6.0 to 6.1. So there might have been a change for atom services too.
Anyway when I try http://<server>:<port>/liferay/api/secure/atom I get a resource not found error message. Whereas with http://<server>:<port>/api/secure/atom I get an access denied so I think the latter is the correct one.
I'm pretty sure I have to add an "allow = myIP" somewhere to get access to it. The big question mark is where? Which file should I change to allow connections not only from 127.0.0.1 but also from my remote IP for atom webservices?