This is Chris, the lead coder for Explorer2260..
Seer is right, ATM it is Linux only and development is slow because I have a full time job and other responsibilities. It is still in development, but there's not much to discuss, as the feature spec is fixed, it's just a matter of getting everything working and I'm working at my own pace and on other projects and my life. It'll almost certainly be open source, so when it is released it could be ported, but I can't promise timelines or how hard it would be to port (in any event, it will need a hardware accelerated complete OpenGL 1.3 implementation, maybe OpenGL 2 for some things.)
As for why it has taken several years, don't go there. I really don't want to open old wounds.