This could provide some viable counterattack to citizen united and PACs.  The full report via link has lots of facts and is very interesting.  This could have big ramifications for some of these PACs and their donors.  

WASHINGTON -- For years, the IRS has done little or nothing to check the rise of overtly political groups that claim a special tax-exempt status in order to funnel secret money into election-related advertising.

But in a sign that the agency may be waking from its slumber, the IRS has sent detailed questionnaires to several Tea Party organizations -- and possibly other political groups -- to determine if they truly qualify for the 501(c)(4) designation intended for groups whose exclusive purpose is to promote social welfare.

Should any group currently calling itself a 501(c)(4) have its designation denied or revoked, tax experts said the consequences could be severe, including fines of 35 percent or more of the money they raised in secret.

And the groups might have to make donors' names public.

Even loose talk about donor secrecy no longer being guaranteed could put a screaming halt to the extraordinary flow of money into these groups from deep-pocketed people and corporations that want to buy political ads without leaving fingerprints.