We combine measurements of Cosmic Microwave Background anisotropies, Supernovae luminosity distances and Baryonic Acoustic Oscillations to derive constraints on the dark energy equation of state w in the redshift range 0<z<2, using a principal components approach. We find no significant deviations from the expectation of a cosmological constant. However, combining those datasets with expansion rate measurements, we find a slight preference for w<−1 at low redshift, thus highlighting how these probes favour a non-constant w. Nevertheless the cosmological constant is still in agreement with these observations, while we find that some classes of alternative models may be in tension with the inferred w(z) behaviour.