Confidence regions in the (\omegam-\omegal) plane from the 42 distant SNe~Ia in Perlmutter \etal\ 1999, overlaid with simulated contours illustrating the improvement in the determination of these parameters that will be possible on the timescale of this survey.  The simulated 2-$\sigma$, 3-$\sigma$ contours (confidence levels as indicated) are based on three advances over the current results:
1) the full 5-year dataset of the proposed SNLS survey. 
2) a dataset of 200 well-measured SNe~Ia  from, for example, the Nearby Supernova Factory, and 
3) a gaussian prior on $\sigma(\omegam) = 0.03$  (centered in the simulation on $\omegam = 0.28)$  reflecting the improvement anticipated from large scale structure and CMB measurements. 


Confidence region in the  ($<w>$-\omegam) plane, assuming a flat universe, from the 42 distant SNe~Ia in Perlmutter \etal\ 1999, overlaid with a simulated 1-$\sigma$ contour illustrating anticipated improvement.  In this case, the simulation was based on only a mid-project SNLS dataset (300 SNe),  along with the same assumptions as in Fig. 2 for the nearby SNe and the prior on \omegam.  
The simulation was done assuming $w=-0.8$ and demonstrates the ability to test whether  a cosmological constant fits the data or if some other model of dark energy is required.