It's now PR4 on the homepage with most of the directory pages PR3 and a few PR0. Much to my surprise I just recently found that the site now has sitelinks for one of the main sub-topics/keyword phrases for the niche topic, and it's ONLY the pages related to the KW phrase that has the sitelinks and are included in the sitelinks that have PR3.
The pages that don't have PR are definitely within the overall topical area and relevant to the site, but they aren't specifically semantically close to the phrase/topic that has the sitelinks and that the other pages are very closely semantically related to.
I hope this is clear enough, it's 6am and sleep is beckoning. ;)
>>All those pages have the same internal linking (with evidence that some global (boilerplate) navigation is being discounted).
>> The pages included in the sitelinks have PR3.
>> The pages not included in the sitelinks show a grey-bar.
I'm convinced that some degree of keyword co-occurrence is playing into this, and also have a nagging suspicion that it may be possible that there might be some topic-sensitive PageRank calculations edging their way into the mix.
[edited by: Marcia at 1:18 pm (utc) on Sep. 11, 2008]