Pagination, the practice of segmenting links to content on multiple pages, affects two critical elements of search engine accessibility. For many years, Google’s recommended that pages contain no more than 100 links (internal or external) in order to make it easy for spiders to reach down deep into a site’s architecture. Many SEOs have found that this “limit” isn’t hard and fast, but staying within that general range remains a best practice. Hence, pages that contain many hundreds or thousands of links may inadvertently be hurting the access of search engines to the content-rich pages in the list making pagination essential.
http://www.seomoz.org/blog/pagination-best-practices-for-seo-user-experience