Bernard Lietaer (former central banker, successful currency speculator, one of the architects of what today is the Euro, and nowadays complementary currency advocate) starts most of his post-crisis conferences by asking the public to raise their hands if they believe that the worst of the crisis is past/ahead of us. Generally, most people will raise their hand to state their belief that the worst is still to come. Here's an example, in front of an audience of financial journalists:
That doesn't necessarily mean you shouldn't buy stocks.
It is extremely unlikely that you will time the bottom of the market just right. So even if it will continue to get worse for a while, it might still be a good decision to continue buying into the market so that when the bottom does hit, you will have bought some stocks right around that time.
This all depends on your investment horizon, etc. etc.
http://www.youtube.com/watch?v=OfMbYllbN6c
(Skip to 2:40 for the actual start if you want.)