We announce the discovery of the second transiting hot Jupiter discovered by the Trans-atlantic Exoplanet Survey. The planet, which we dub TrES-2, orbits the nearby star GSC 03549-02811 every 2.47063 days. From high-resolution spectra, we determine that the star has Teff=5960+/-100 K and logg=4.4+/-0.2, implying a spectral type of G0 V and a mass of 1.08+0.11-0.05 Msolar. High-precision radial velocity measurements confirm a sinusoidal variation with the period and phase predicted by the photometry, and rule out the presence of line bisector variations that would indicate that the spectroscopic orbit is spurious. We estimate a planetary mass of 1.28+0.09-0.04MJup. We model B, r, R, and I photometric time series of the 1.4% deep transits and find a planetary radius of 1.24+0.09-0.06RJup. This planet lies within the field of view of the NASA Kepler mission, ensuring that hundreds of upcoming transits will be monitored with exquisite precision and permitting a host of unprecedented investigations. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among Caltech, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.