In Australia we have something called the GFPT or General Flying Progres Test... it's sort of an interim 'restricted' licence that allows you to fly with passengers in the local training area, with your instructor's approval. Typically, new pilots would be at this stage at around the 30-35hr mark.
I think it's a great idea for getting used to handling pax, slowly. You're flying in a familiar environment (depending on which airfield you fly from you're essentially in sight of the field at all times, but certainly flying in a location you've been in many times before) and since you need your instructor to sign you out, difficult weather decisions etc are taken away from you. You're essentially still under an instructor's supervision.
My first passenger was my mum, I took her up approx 30 minutes after passing the GFPT flight test! I then did maybe 8-9 hours of local bimbles with mates over the next few months before I kicked off the navs. At that stage of my flying training it was great experience.