Well well… it seems Mitt Romney requested his VP candidates, including the one he eventually selected, submit 10 years of full tax returns for review. The Daily Beast reports:
The requirement was consistent with the past practices of both Republican and Democratic campaigns. Indeed, in 2008, Mitt Romney turned over 23 years of taxes to John Mccain’s campaign when he was under consideration to be the Arizona senator’s running mate.
But this year, the vetting of tax returns has had particular political resonance because of Romney’s refusal to release more than two years of his own tax filings.
But that’s not accurate, considering Romney’s 2010 return is still incomplete without disclosure of his foreign accounts abroad, and the 2011 return is only an estimate. As we wrote back in August:
…why continue the claim that releasing Mitt’s returns would give Obama “more ammunition” if there’s nothing to hide? If Mitt participated in the IRS’s 2009 tax amnesty program, as he definitely could have, then in fact Romney was doing something illegal.
We can only speculate.

Mr. Romney, you have asked us whether or not we are better off than we were four years ago. (The answer for me is, yes.)
But I would like to ask you the same question:
Are you better off than you were four years ago?
Please confirm by showing me your tax returns for the years in question.
Release the tax returns!