  We combine recently computed models of stellar evolution using a new
treatment of rotation with a Bayesian statistical framework to constrain the
ages and other properties of early-type stars. We find good agreement for
early-type stars and clusters with known young ages, including beta Pictoris,
the Pleiades, and the Ursa Majoris Moving Group. However, we derive a
substantially older age for the Hyades open cluster (750+/-100 Myr compared to
625+/-50 Myr). This older age results from both the increase in main-sequence
lifetime with stellar rotation and from the fact that rotating models near the
main-sequence turnoff are more luminous, overlapping with slightly more massive
(and shorter-lived) nonrotating ones. Our method uses a large grid of
nonrotating models to interpolate between a much sparser rotating grid, and
also includes a detailed calculation of synthetic magnitudes as a function of
orientation. We provide a web interface at www.bayesianstellarparameters.info
where the results of our analysis may be downloaded for individual early-type
(B-V<~0.25) Hipparcos stars. The web interface accepts user-supplied parameters
for a Gaussian metallicity prior and returns posterior probability
distributions on mass, age, and orientation.
