A few minutes ago, i was fighting with a friend about a page’s pagerank, he was seeing PR0 and me PR3. It seems the difference came from a letter in the link ( http://en.wikipedia.org/wiki/IPhone vs. http://en.wikipedia.org/wiki/Iphone ), so it seems that Google is case sensitive so you should be careful when putting links directly to a page, because it may see two different pages.
via alex of devicepedia

January 12th, 2007 at 8:39 am
Maybe he was checking PR in other DCs, since the update is in progress
January 21st, 2007 at 6:24 am
It probably has more to do with Wikipedia being case sensitive (which I think is STUPID, if anyone cares…)
Wikipedia has separate entries for each of the two links you sited, which is why Google had different ratings; they are two different pages. The “Iphone” entry just redirects to the “IPhone” page.
Try funky case combinations to check for the ranking of other (non-case-sensitive) pages, I doubt you’ll see any difference. Or maybe you will…
January 24th, 2007 at 11:05 pm
Yes, this is well known. The PR of a particular URL also depends on whether you include the ‘www’ or ‘index.htm’ terms as well. If I exchange links I always specify the exact URL I want used.