For example, spending on entitlement
programs, such as social security, drift higher without a vote of
Congress each year. These programs can be changed or even terminated
with an act of Congress, but normally the spending growth on the
mandatory side of the budget rolls on, immune to the day-to-day
political haggling that otherwise engulfs Washington. That inspires
looking at discretionary spending alone to gauge how much more, or less,
the government agrees to spend in any given fiscal year. Here too
there's been a sharp drop in the rate of spending, albeit only in fiscal
year 2011. But the change is dramatic: discretionary federal outlays
for fiscal year 2011 dropped slightly relative to the previous fiscal
year.

Keep in mind that federal spending is a direct byproduct of Congress,
albeit with a heavy hand of influence from the White House. In other
words, the idea that federal spending, for good or ill, flows from the
decisions of one man, or one branch of government, is misleading, to say
the least. Obvious? Yes, but worth repeating in a highly charged
political season.
As for the federal budget numbers, they are what they are. You can
attack the data as evidence of a government run amuck, or praise the
numbers as evidence of enlightened governing. But whatever you do, don't
attack the messenger for reviewing the facts.
Update: Here's an excerpt from the aforementioned "Budget and Economic Outlook: Fiscal Years 2012 to 2022" from CBO (pages 4-5):
Federal spending rose by 4 percent in 2011, to $3.6
trillion—a rate of increase that is significantly less than the nearly 7
percent average rate of growth in federal outlays over the previous 10
years. About half of the $142 billion increase from 2010 to 2011
occurred because downward revisions in the estimated net cost of the
Troubled Asset Relief Program (TARP) in 2011 were smaller than in 2010;
those revisions were recorded as reductions in outlays. Excluding the
TARP, total outlays grew by $70 billion, or about 2 percent. In 2012,
CBO projects, outlays will increase by just $3 billion (or 0.1 percent).
As a percentage of GDP, outlays will fall from 24.1 percent in 2011 to
23.2 percent this year—a level still higher than
in any year between 1984 and 2008.