  The new 182 gold supernova Ia data, the baryon acoustic oscillation
measurement and the shift parameter determined from the Sloan Digital Sky
Survey and the three-year Wilkinson Microwave Anisotropy Probe data are
combined to reconstruct the dark energy equation of state parameter $w(z)$ and
the deceleration parameter $q(z)$. We find that the strongest evidence of
acceleration happens around the redshift $z\sim 0.2$ and the stringent
constraints on $w(z)$ lie in the redshift range $z\sim 0.2-0.5$. At the sweet
spot, $-1.2<w(z)<-0.6$ for the dark energy parametrization $w(z)=w_0+w_a
z/(1+z)^2$ at the $3\sigma$ confidence level. The transition redshift $z_t$
when the Universe underwent the transition from deceleration to acceleration is
derived to be $z_t=0.36^{+0.23}_{-0.08}$. The combined data is also applied to
find out the geometry of the Universe, and we find that at the $3\sigma$
confidence level, $|\Omega_k|\alt 0.05$ for the simple one parameter dark
energy model, and $-0.064<\Omega_k<0.028$ for the $\Lambda$CDM model.
