Just how accurate is the CBO?

Supporters of the healthcare bill have been dancing in the streets since yesterday's report indicated that the Congressional Budget Office projects a $132 billion savings over 10 years on a bill that will cost $940 billion.

Notwithstanding the fact that the CBO numbers:

• Are preliminary;
• Don't take into account the impact of the House reconciliation bill; and
• Have an overly optimistic assumption that government bureaucrats will figure out how to cut costs of Medicare and Medicaid without cutting services....

The real question here is: just how accurate is the CBO?

Here's a quote from a Newsweek article last fall about how accurate the CBO numbers will be on healthcare:
While the CBO puts together its most comprehensive prediction possible, it often gets it wrong with big health legislation. It's not a lack of expertise or bias that causes the predictions to miss the mark, says Stuart Altman, a Brandeis University economist: "The problem is what we're asking them to do is impossible." Health-care legislation is the toughest to score accurately, says Robert Reischauer, former CBO director, because unlike laws that change the tax code or budget new building projects, there are often no data to examine.  -- Newsweek, October 8, 2009.

Another article examining the accuracy of the CBO in the past, says that the CBO projections are less accurate than an astrology horoscope.