Age plays a factor in determining PR, ad well as "nofollow" links now, and .edu links, trust me this is the truth!!!
domain age and TLD/ccTLD dosent matter for pagerank...what matters is pagerank of backlinking page, dofollow status & no. of outbound links on it.
God knows how google works that out our site is currently number 8 for Spanish property (19m) number 8 for Spanish properties for sale (6m) and number 9 for Spanish property (15m) the most searched keywords for spanish property and number two for Spanish property in Spain (34m) and we have over 2000 backlinks (including pr 7s and Yahoo dir pr8) according to yahoo and 11000 pages and lots of good content but we only have a pr3. Now I understand that we are in a very competitive marketplace but surely that shouldnt effect our PR. What it does show is you dont have to have high PR to rank high on google searches. Obviously the only problem is getting reciprocal links from pr 5 and pr 6 sites. I see some sites with very little content getting pr4 relatively easily and always wondered how