Thank you for your warmness and understanding,
My pleasure, Keith.
That's something I've been curious about. "Ghost PR" is probably based on the PR of other pages within the domain. It's a temporary estimate based on the idea that the page is "likely" to end up with a given PR (AFAIK).
But how long does it stay that way? Obviously, once the page gets indexed, the toolbar is going to display a more accurate estimate of its PR, but what if it never gets indexed, say because the URL contains a session ID? Will the ghost PR eventually go away and get replaced by a blank?
As you noted, once the page gets indexed, it shows a "real" toolbar PageRank.
There appears to be a time when it will sometimes show a gray PR or even a white PR for an interim period. I believe it may be between the time that the spider finds it, until it adds it. But I haven't studied this extensively. I've just noticed it on my Newsletter Archives.
At first they show the inherited PR (ghost PR), and then they show gray or white (I can't remember which it is). And then it gets it's real PR.