have a look here: http://www.irs.gov/pub/irs-pdf/f1098t_08.pdf On the last page is a set of instructions for filers. You should be able to root around on the IRS website and get an idea as to what you need to do.
I don't know what kind of money you make, but that you would pay it for 2008 when your tax situation didn't change much is very suspicious. They increased the exemption through the AMT patch, but they didn't change the pase-outs which start at $150,000 for MFJ. I recently gained a client because TurboTax completely butchered his AMT calculation. It is possible you had the same thing happen. I'd take a close look at the Form 6251 and see if the calculation makes since to you there. Once you start hitting AMT, it may be worth having a CPA. Did you itemize or take the standard deduction.
I hope they don't check my return too close -- I made 8 extra deductions for a recent octuplet birth.