2,300 pages of indexible content? Did you come out of the gate with that many? I mean, is this a fairly new launch, within the past 12 months?
How do you determine the visits to your Supplemental Pages? Are you tracking your pages in this SI over periods of time? Are you watching the movement of those pages across the various indices that Google have?
How are you determining the number of pages that Google have indexed from your site? What does Yahoo! show? Live?
Yes, that number is a bit low. But, if the site is "fresh", I'd expect that. If it is over a year old, then there may be other issues at hand from a technical standpoint that have yet to be discovered?
You are absolutely correct. Trying to spread that little bit of PR across 2,300 pages is not going to work. I'm sure there is some sort of scale that could be used that says if your site is PR3 at the root level, you'll only get 100-250 pages into the index at a "seated" level. Those at the top of the click path and/or those with the most links pointing to them. The rest of them will fluctuate in the "Rolling Index" until such time that enough history has been established for Google to do further calculation.
[edited by: tedster at 6:46 pm (utc) on Dec. 19, 2007]