What are the eligibility requirements?
For the 52nd Annual GRAMMY Awards, albums must be released between Oct. 1, 2008 and August 31, 2009. Recordings must be in general distribution in the United States, i.e. sales by label to a branch or recognized independent distributor, via the Internet, or mail order/retail sales for a nationally marketed product.

from here: http://www.grammy.com/GRAMMY_Awards/Voting/FAQs/