One of the best ways to find out how Google ranks sites is to look it's own tools like Google Advanced Search. I haven't used Yahoo Site Explorer in a while but I'll have to so I can use She Told Me Scoops to build backlinks to things that are linking to my site. Unfortunately, it's a pain to see links built to individual pages with Yahoo Site Explorer leaving an opening for a good paid tool(Hoping for free).
Anyways, Webmaster Tools shows the number of domains and the number of pages each domain is linking too. This sort of validates my theory about The Power of Content and the importance of building the size of your site. Each new page gives a new opportunity to link to a new page from the same domain increasing the metrics of your site. So, it would seem that it's not a C-class IP penalty but top level domain penalty.
Webmaster Tools also lists your top ranked pages and how many individual domains are linking to each page. Of course Google also lists the anchor text that's linking to your site in Webmaster Tools.
So to maximize ranking using the new Google Webmaster Tools data:
One link per domain for each page using your anchor text. I don't think anchor text variation will save you and allow you to link to one page from the same domain anymore(I don't have that thought I mean, I'm not saying that that was true and now isn't). You need to vary the domain and the page linked to as well.