As far as I know, most of our players who play online use Skype.
My American sales team just introduced an interesting alternative to me called
ooVoo. The free service offers up to 12 people in simultaneous video/audio chat. This is equivalent to Google+ Hangouts, but that service is highly unreliable for me here in China.
I'm not sure how well a 2v2 online game of PG would go, but thought you folks would like to be aware of this alternative. It's kind of neat to imagine a situation with players literally from all around the world working through a scenario together.
I have an ooVoo account now. So if you also decide to try it PM me and I'll send you my ID.