Page Rank is *part* of how Google scores search results. Lucene cannot easily use Page Rank however as you have to post-process the sites you've indexed, make calculations on how the sites are linked together, and then update the index with this info.


The Anatomy of a Large-Scale Hypertextual Web Search Engine

The PageRank Citation Ranking: Bringing Order to the Web

Citeseer is a great repository of technical papers and will show papers that describe or refer to Page Rank:

There is a java implementation of page rank: