First of all closely watch this Friday's CPI (Consumer Price Index) index release, then closely follow other price index releases like the producer price index on the 17th. If the CPI trends to anything more "normal" then expected prepare to see a spike in U.S. treasury yields and a boom in stock prices. If the CPI stays the same or trends downward then bond yields will go lower as deflation would make the return on bonds -depending on how bad deflation got- attractive. In that case expect to see a significant decline in equities. The element that's hard to account for, the human element, will play a huge role. If investors get tired of the low treasury yields or if some happen to run hedge funds that promise wonderful returns, then there will be a greater incentive to take risks, and bond yields spike and the stock market rally.
Furthermore, depressing news from Europe like the recession in Greece worsening, any more bank failures and bailouts (Goldman Sachs perhaps?), and last but not least the Federal Government bailing out states that can't fulfill their debt obligations could also lead to treasury yields going lower. As one can see we are certainly in some rocky waters.