The year 2008 has witnessed remarkable steps in developing high energy neutrino telescopes. IceCube at the South Pole has been deployed with 40 of its planned 80 strings and reached half a cubic kilometer instrumented volume, in the Mediterranean Sea the "first-stage" neutrino telescope ANTARES has been completed and takes data with 12 strings. The next years will be key years for opening the neutrino window to the high energy universe. IceCube is presently entering a region with realistic discovery potential. Early discoveries (or non-discoveries) with IceCube will strongly influence the design and the estimated discovery chances of the Northern equivalent KM3NeT. Following theoretical estimates, cubic kilometer telescopes may just scratch the regions of discovery. Therefore detectors presently planned should reach sensitivities substantially beyond those of IceCube.

Invited Talk, International Symposium on High Energy Gamma-Ray Astronomy, Heidelberg, July 2008, 12 pages, 11 figures