Here he is back in 1993 discussing some design philosophy, then demonstrating ColorFORTH and his homebrew chip design software. The second video is particularly amazing.
If you were ever wondering what Bill Joy was thinking when he was pushing SPARC you need only read this book. I had a copy of it in my office. Challenge of course in stack machines is that at the time, the memory for stacks was very very expensive and slow, and so you got things where the top 'n' levels of the stack were 0 waitstate ram on the CPU and then a 'fault' function to free up more space if you needed it.
These days you could build a machine that was both VLIW and pure STACK and it would be very fun indeed.
www.greenarraychips.com
Plus his site showing off his ColorFORTH OS that he uses to design his chips by hand:
http://www.colorforth.com/