http://www.arts-union.ru/node/23
It’s all Russian but i tested it and it seems to be better than both Virtual Jaguar or Project Tempest. I couldn’t make the sound work for some reason but i don’t know if i did something wrong or there is a lack of sound emulation.
I have no idea if this emulator is open source either. But if it is, it could be a better solution for a Jaguar Core.