A third party comment system is one that Facebook has fully exploited:  This sytem means that you can log in with Google, Yahoo or Twitter with Facebook ID.

 

According to TheNextWeb.com, a third party Google comment system would ensure that users are further plugged in to their Google accounts, and one step closer to Google+.

It is not clear how successful this will be especially for Google+ but a Third Party Comment Platform is the way to go.