Related note: when I bought R2012a about a week ago, early August 2012, the "one year" software support subscription that was provided extended to at least the end of September 2013, so I should receive R2012a, R2012b and R2013a and R2013b all with the one purchase.
By the way, they're calling R2012b "Version 8.0". I guess they think it's a more substantial change than the prior 14 versions of version 7. Actually I wish they'd just drop that number version and just go with the year version numbers. I never know what people are talking about when they say "I'm using version 7.5" but it's clear when they say R2010b or whatever.