More and more info is being discovered about B12. Here are some of the best studies and articles that I have found.

http://the-moneychanger.com/articles_files/health/vitamin_B12.phtml 
http://www.westonaprice.org/basicnutrition/vitaminb12.html
Http://www.mayoclinic.com/health/vitamin-B12/NS_patient-vitaminb12
http://www.ox.ac.uk/media/news_stories/2008/080909.html