I'd be surprised if anyone did anything with it at all considering that there's been nothing stopping people interested in xcore microcontrollers from having a go at it for the low price of 100 USD with kit directly from XMOS. We've had what, two years now since this was all announced? I've seen nothing from the hobby hackers.
You obviously haven't been paying attention then.
We've had several interesting projects created with XMOS hardware.
But Piru is right, there is not enough bandwidth for emulating hardware as complex as a 68K.
I, myself, was looking at 6809 emulation with this hardware (closer to its capabilities).
Really, the Xena port is more of hacker oriented I/O port.