Depression.
In fact, the economy is currently being ARTIFICIALLY STIMULATED by the approaching tax-rate increases on January 1st. Watch for crash on or before January 1st, as businesses and individuals cease economic activity that will no longer pay in 2011.
It won't even have to be a conscious decision, although I'm sure it will be partly. But, the fact of the matter is the people who are primarily responsible for capital formation in a free market - higher income earners and producers - will have less to invest and spend as the fedgov begins to take a bigger chunk.
This might account for some increase revenue to the Treasury, but that will be short-lived as the economy begins to slow, again (assuming it ever really began to pick up. Eventually, what is happening in California with respect to disappearing tax receipts will happen federally, which will spur the liberals to call for even higher taxes - it's a death spiral which we probably won't get out of until Obama is beaten, hopefully.