After you shake off your hang over, get ready to do some simple math. You're going to change your W-4 today. Or if you're like me and paid in 1099s, calculate your estimated taxes.
2011 tax tables aren't out yet, but due to low inflation and the Republican HoR, it's very unlikely that the rates will change in 2011 (though there is a chance of an Social Security tax break. Your HR department will handle this unless you're a 1099 contractor like me).
The IRS W-4 calculator is here. Be sure to include dependents you may acquire during the next tax year.
For 1099 employees, use the 2010 numbers and refer to this post.