Here's the official word from ATR:
ATR has consistently maintained that individual Members of Congress make a pledge to their constituents to oppose and vote against tax increases. The House this week will vote on a tax bill. This legislation—popularly known as “Plan B”–permanently prevents a tax increase on families making less than $1 million per year. Republicans supporting this bill are this week affirming to their constituents in writing that this bill—the sole purpose of which is to prevent tax increases—is consistent with the pledge they made to them. In ATR’s analysis, it is extremely difficult—if not impossible—to fault these Republicans’ assertion.
Some (*ahem* Wall Street Journal) thought this was the Grover stamp of approval on Plan B but the ATR statement was updated later to say that it is "not to be misconstrued as an endorsement of any legislation."
Perhaps this was done to clarify things for the record OR it was a wink to the boys at the Heritage Foundation who ARE NOT down with Plan B. Here's part of their statement via the Atlanta Journal Constitution:
On Thursday, the House is expected to vote on “Plan B,” which would allow tax rates to increase on some Americans and small businesses. The plan is based on an idea floated by Senator Chuck Schumer (D-NY) in 2010 and endorsed by House Minority Leader Nancy Pelosi (D-CA) earlier this year.America’s coming fiscal crisis is a result of overspending, not under-taxing. Allowing a tax increase to hit a certain segment of Americans and small businesses is not a solution; it is a political ploy.[…]Heritage Action opposes “Plan B” and will include it as a key vote on our legislative scorecard.
Avoiding the noose of Norquist is really anyone needs to worry about though, right?