I received an email from Kelly, the operator of HamSphere, a "virtual ionosphere" (i.e. VOIP ham radio emulator) to say that the system has closed. It doesn't surprise me, since the system was free, and the cost of the web hosting and bandwidth must have been considerable.
I have said before that I don't really see the attraction of pretending to make ham radio contacts over the internet, no matter how QTH-challenged you are. But some people do, and I expect they will miss HamSphere.