To be honest I'm hearing for the first time about SONM, and from the table that @helloge showed seems that there are many good features comparing to Golem.

How have they think to implement SONM in game servers? Players can earn money while playing or it will be used only for in the game coins/packages as a form of payment like Paypal?

They idea seems to be good but since it is not yet launched then better stay with Golem or with none of them until the SONM gets released for the public.