The IRS's Whistleblower Office has released its FY 2012 annual report to Congress:

In FY 2011, the Whistleblower Office paid the first claims under § 7623(b). Five claims have been paid under the revised law. … During FY 2012, the IRS received 332 whistleblower submissions relating to 671 taxpayers that, based on the face of the submissions, appear to meet the threshold of $2,000,000 in tax, penalties, interest, and additions to tax in § 7623(b). Many of the individuals submitting information to the IRS claimed to have inside knowledge of the reported transactions, often including extensive documentation in support of their claims. The IRS does not yet know how many of these cases will result in collected proceeds after examination or investigation, as the amounts alleged reflect only the whistleblower’s estimate of the potential recovery. Twelve of 128 claims paid in FY 2012 involved collections of more than $2,000,000.