The S&P broke under the trendline that runs from the 2007 high through the 2011 double-top. You can make a case that it is testing a trendline that runs through the 2009 lows through the 2011 bottom on a weekly chart. Should the fall continue, additional areas of support to watch for are 1260-ish, which held twice in early 2011, and 1150 area.
Despite the apparent potential support, I remain bearishly inclined as the overwhelming weakness in commodities makes me think the U.S. and Chinese economies are in worse shape than the market is currently pricing in. I suspect that while the market is focused on the European debacle, recession in the U.S. and China are the things it must fear most. Time will tell, but things are certainly getting interesting!