By combining data from seven cosmic microwave background experiments ( including the latest WMAP results ) with large scale structure data , the Hubble parameter measurement from the Hubble Space Telescope and luminosity measurements of Type Ia supernovae we demonstrate the bounds on the dark energy equation of state w _ { Q } to be -1.38 < w _ { Q } < -0.82 at the 95 \% confidence level .
Although our limit on w _ { Q } is improved with respect to previous analyses , cosmological data does not rule out the possibility that the equation of state parameter w _ { Q } of the dark energy Q is less than -1 .
We present a tracking model that ensures w _ { Q } \leq - 1 at recent times and discuss the observational consequences .