Link Popularity
There are many ways to increase your link popularity but every link has a different value for google and other search engines for example a link in a directory will carry lesser weight and a link which is within the content on a very relevant page to your own site will have much more weight and will benefit the most.
Google constantly updates its search engine algorithm and keeps seo experts on their toes as nothing is static for them they just keep giving shocks.
The newest thing is their algorithm which will find out the relevancy between text on the page where the link is and the page where it points to for evaluation purposes and this should change things all together as those sites who have been purchasing links on irrelevant pages just to gain some PR will loose out and the natural links will gain more importance.