Summer is only beginning, but many digitally savvy parents are already starting their back to school shopping research, and brands are just starting to lock down plans for back to school initiatives -- which, for some brands, is the biggest time of the year. Brands need to start marketing right now to reach these early researchers, and there's no better place to do so than on Facebook, which has become the best social media channel to reach and engage with back to school shoppers, boasting much greater reach and influence than sites like AOL, Yahoo, and MSN.   In 2011 social medi...