Dave, there's a difference between a page with a list of outbound links, like a directory or a links page, and a content page on a site, like the homepage that would lead to product pages.
Well yes there is. But not as far as Google assigning PR to the links on that page go. Besides this, why do you bring up this point? The subject is "importance of location of link on page" not "importance of location of link on a content or homepage" :o)
If we were working on a search engine and sat there looking at a web page, what would we look for on that page in order to decide how to construct an algo to best reflect the page's relevance?
Lot's of factors, but I doubt that all the ones beggining with the letter "A" would be given more weight that the rest. In others words, IMO a links position on a links page would not be taken into account. It it were, all links that have anchor text starting with "A" would all have the higher PR.