  We report new results of Bose-Einstein condensation of polaritons in
specially designed microcavities with very high quality factor, on the order of
$10^6$, giving the polariton lifetimes of the order of 100 ps. When the
polaritons are created with an incoherent pump, a dissipationless, coherent
flow of the polaritons occurs over hundreds of microns, which increases as
density increases. At high density, this flow is suddenly stopped, and the gas
becomes trapped in a local potential minimum, with strong coherence.
