According to the Washington Post here, a Senate panel will be releasing a report today discussing tax shelters.  The aim is to crackdown on shelters that some may consider legitimate, but others find clearly illegitimate. Issues of "advice of counsel" may play a factor in some of these shelters where some acted on the advice of people who thought the shelters legal. 

Two Observations:

• People who take these risks often find themselves paying more.
• Clarity in the law always works to everyone’s benefit.

(esp)

Addendum – See also the Tax Blog here and here.