futureX - 10:00 am on Sep 21, 2010 (gmt 0)
Most of my sites are small and probably quite niche, but they all seem to grab good rankings above older sites even in the absence of any page rank.
Generally for a brand new site it seems like maybe 1 - 2 months for rankings to stabilise as google finds all the backlinks and indexes the whole site. And in most cases I would probably agree with the rankings that google has assigned based on the authority of the sites that my pages go up against.
I would say that for sure that Page rank and age are not a big barrier in the hunt for good serps.
This may be different for highly trafficked and sought after keywords though...