Dynamics of Cats predicts the next Milky Way supernova. They occur within a galaxy of our size every 50-100 years on average, and yet we haven't seen one on our side of the galaxy for at least three centuries, which means we're due* [*statistically ignorant statement added for effect]. He goes on to note that several important instruments which would be extremely nice to have around if a supernova goes off, will be going off-line themselves in 2008-2009. Thereby ensuring that such an event will take place during that time, through the inescapable tenets of Murphy's Law. Among the observatories closing for business:
Meanwhile, Hubble is still missing its main camera, with only mixed efforts for rehabilitation (newsflash: space missions are dangerous) and the Webb Telescope not online until ~2013. There'll still be all the usual ground based radio, IR, optical, Chandra etc. But it is certainly troubling that we're coming up on this gravity wave blackout as well as a shaky Hubble and Spitzer -- all simultaneously. So if a supernova during this time explodes we'll be missing out on a lot of interesting kinds of data.
Of course, SNEWS is going strong, and with approximately 35 neutrino detectors working all the time we're pretty much covered there. Unless they all spontaneously break again. Too bad neutrinos get no respect.