Langevin dynamics perturbs the velocities, based on a collision frequency (FBETA), which is related to viscosity, and the temperature. It is distinct from Verlet in that energy is not conserved, and it approaches Brownian dynamics behavior in the limit of a large FBETA value (high viscosity). It can be used to regulate T, but a real thermostat is preferred; with Langevin dynamics, the time scale is somewhat arbitrary, and requires careful calibration for comparison to experimental time values.
There's a good treatment of T regulation methods in the book
Computer Simulation of Liquids
Oxford Science Publications
M. P. Allen, D. J. Tildesley
ISBN-13: 978-0198556459 ISBN-10: 0198556454
A brief explanation of Langevin dynamics can be found here