To implement an identification system descentralized OpenID consumer plugin seems to bea good option.

I see that this is already in the roadmap of wiserearth, but I don't know if is dificult to implement. There is a plugin for symphony framework that maybe can be used...

The Plugin is called: sfOpenIDPlugin and is only for consumer functions not provider... but maybe coul be implemented in short time... ¿?

http://trac.symfony-project.com/attachment/wiki/sfOpenIDPlugin/sfOpenIDPlugin-1.0.0.tgz

Related to existing suggestion on OpenID here