It's a huge, mapped out web of government spending.
From their website:
"Death and Taxes:2009" is a representational poster of the federal discretionary budget; the amount of money that is spent at the discretion of your elected representatives in Congress. Basically, your federal income taxes. The data is from the President's budget request for 2009. It will be debated, amended, and approved by Congress by October 1st to begin the fiscal year.
The poster provides a uniquely revealing look at our national priorities, that fluctuate yearly, according to the wishes of the President, the power of Congress, and the will of the people. If you pay taxes, then you have paid for a small part of everything in the poster."