I'll base my assessment of the same criteria I used in my previous blog post "Bearish Sign: Extreme Bullishness for US stock market" published on the 7th of April 2011.
Since that time, Investor Intelligence does not freely publish its Bull/Bear Ratio and you have to be a paying member to access this information (which I'm not). However, I found a study published on the 31st of July 2011 that makes use of this data (Up to 26 July).
So on the 26th of July, the bull bear ratio was around 2.3. It has certainly dropped below 2 since then considering the sharp decline in the S&P 500. But we can't really that to make a decision.
The 14-day Relative Strength Index (RSI) for the S&P 500 is about 24 , which is usually a sign of an oversold market at least in the short time.. However, notice that the S&P 500 (below) has broken the bullish trends it started in March 2009.
Finally, let's have a look on the percentage of stocks above their 200-day moving average.
23 percent of stocks are now above the 200 MA, this is a level not seen since the market crash of 2008, and could indicate stocks have not much further to drop.
To conclude, if you believe that central banks will come to the rescue (say Q3) if the market falls further (as Marc Faber does), this may be a pretty good time to buy stocks (in the US or abroad) or add to your positions. However, if they wait and see, the market could fall much more (before it goes up again) especially if advanced economies falls into recession or the long awaited slowdown of the Chinese economy materializes.