Planet13 - 7:49 pm on Jul 4, 2013 (gmt 0)
My internal pages mostly have a toolbar PR of 3, and most have 3 to 6 (it can be anywhere from zero to 20 though) in-content links, plus navigation and link to category. Seems reasonable to me.
I am going to go out on a limb and state that google is probably quite good at looking at the links in the navigation bar, category tree, breadcrubs, etc (i.e., general navigation links), and that if you have any problem DUE TO INTERNAL LINKS it would be from the internal links.
I say that because we have seen google implement "above the fold" updates, which require google to better understand page layout, as well as recognizing breadcrumb links, which again requires an understanding of where one page section (navigation) ends and where "content" begins.
So I wouldn't worry so much about the navigation links.
Have you used your analytics to see how often users CLICK those links?