Reply to Marcia post.
I checked with Yahoo link: search. Even now there are no inbound links except from my site. But at the time when this page got PR2 all links to it from my site had PR0 and only more than month later other pages got PR4 without infulence on the rank of the page in question (it is still PR2).
So I still beleave it is pure experiment and *small* PR for the page with no inbound but good outbound links is possible.