Here's a a great link discussing the 2006 tax credit: http://www.fueleconomy.gov/feg/tax_hybrid_new.shtml

Also, the IRS will produce a form or update form 8910 to support 2006 hybrids. They don't have a 2006 form 8910 posted yet, but you can look at the 2005 form here: http://www.irs.gov/formspubs/lists/0,,id=97817,00.html
then choose '2005 Form 8910 Alternative Motor Vehicle Credit' and click the Review Selected Items button.

http://www.taxact.com is a great cheap/free e-file site. I have used them for the past 3 years.

--Matt