Erick Erickson, CNN political analyst and founder of RedState writes:

Someone within the Internal Revenue Service leaked to the gay-rights organization Human Rights Campaign the private Form 990 of the National Organization of Marriage. The form contains a list of major donors to the National Organization for Marriage. The IRS Form 990 is available for public inspection on request, but the law is very clear that donors are to have their information redacted.

... The Landmark Legal Foundation’s Mark Levin, also a popular radio show host, recently highlighted troubling IRS activities against tea party groups. Many tea party groups in the country claim the IRS is attempting to undermine their 501(c)(3) tax status. The IRS attempts go beyond normal tax challenges demanding specific information into family members, outside groups, affiliates, and deep background on individuals involved as officers of the tea party groups.

The use of the IRS as a political tool to intimidate opponents of the government is positively Nixonian, but only because the income tax and IRS were barely out of the fetal stage for Woodrow Wilson.