exactly PR and result position is two different thing
Exam:
make a blog on wordpress(or anywhere else).And be careful to choose some tag for you post(the reason is since your blog is new,while you put a tag such as hosting music php or anything else,wordpress will show you blog on the new post on that tag.And help search engines to index you)
and put strange sentence look like "yoursr abhiy 76jg8o" in your site
after a 2 or 3 week search that phrase.Google or yahoo will show your blog on top result while your page rank is still 0
i hope your realize the diffrent bewtwen PR and resolt positton
but for some keywords which is so popular such as "hosting" , "webdesign" or ...... the search engines first try to show the pages with higher PR ,if higher one is available.
and having high PR doesn't mean that you will be on top result
some other factor such as keyword density or having keyword in tags,topic,url have more backlink is important all together
If you need to be on top for "hosting"
-You need too much back link from sites which they are about hosting
-You need enough "hosting"in your text,topic ,tags ,url(not too much)
-You need many users visit your site
-You need many more that i can not teach you
And consider that they result from different Google or yahoo Data center can be different
and the result is search engines became smarter and know they can realize that they online shop which sell flower in Toronto is good for people who search flower shop from Toronto and flower shop from Tehran is good for people who search flower from Tehran and they make different between users by their IP