Today, Congress has passed a bill including an amending that extends and expands the Homebuyer Tax Credit.  Be sure to click on the NAR link below.  Here are some key points:  

The tax credit for first time homebuyers (those who have not had ownership interest in a residence in the last three years): $8,000 for married couples, $4,000 for those filing separately.

Contracts need to be signed by the expiration date: April 30th, 2010.

Also, those buyers who have maintained ownership of a primary residence for five of last eight years are eligible to receive a tax credit: $6,500 for married couples, $3,200 for those filing separately.

Income limits $125,000 for those filing separately; $225,000 for married couples.

Home purchase price can not exceed $800,000.

Here is a link to the National Association of Realtors President's podcast:
http://www.realtor.org/about_nar/presidents_report/_podcast_archive/mcmillan_taxcreditextended_20091105