It appears that they maybe getting close, but no agreement has been met: http://firstread.nbcnews.com/_news/2012/12/31/16268297-obama-deal-is-within-sight-not-yet-complete?lite&ocid=msnhp&pos=2

From the article: 

But even amid rising optimism that a deal could be reached, just a handful of hours separated Congress from the actual arrival of the cliff. Though Congress could still conceivably act after New Year's to preserve existing tax rates — thereby limiting any lasting effect on consumers — their inability to reach an agreement until the very last minute could still threaten to rattle the economy and markets.

How will you be affected if they do not reach an agreement in time?