Imaging a page with 5 links
link1 to domainA
link2 to domainA
link3 to domainA
link4 to domainB
link5 to domainB "no follow"
60% of link juice will go to domainA
20% will go to domainB
20% will be wasted (no-follow)
The link text for link1 and link4 will pass link text relevancy, the other link text will not pass any relevancy.
Its a bit more complicated than this because the first link passed a bit more then the last.
read http://thatsit.com.au/seo/tutorials/a-simple-explanation-of-pagerank