We currently have an OpenID based Google AppEngine application.
We are now trying to integrate our application with our customers inhouse IT systems and see,hat OpenID is a quite complicated spec to implement.
We also see, that Google is moving in the direction of OpenID Connect (if you look at Google Drive).
Is there any other well known public OpenID Connect provider beside Google?
There's a list of implementations resulting from the OpenID Connect Interop 4 and another list based on published test results from the OpenID Connect test service run by UNINETT. From those two sources I extract the list below (both open and closed solutions, both OP and clients):
Gluu has already been mentioned. Another implementation that looks interesting is eBay's. There is some documentation, but the GIT repository mentioned there didn't work for me.