Search engines love new contents and information. Search engine robots are always hungry to crawl new contents. Social media sites are being filled with new contents every single day, even this very moment- whether it be single posts – comments – lenses or even pages – there is always something new.
Due to the amount of fresh contents being published on social media sites – many search engine robots crawl these sites on a regular bases – if you ask me then social media sites have 100's of robots crawling 100's of pages every minute. (dependant on the social media site of course )
As a result of the new contents and the many people linking back to these sites – they have gained much authority and have excellent page rank. So using these social media sites – if it be facebook – myspace – blogger – squidoo, hubpages or another then there is no doubt that they will help your seo strategy a great deal.