I think they opened up the code for the propeller yes? and you can get an msp430 clone on opecores or an arm2 on opencores as well as the or1k and 2k, plus a myriad of other open source cores there and elsewhere (just google it). The lm32 is open, and the mico8 is maybe, certainly can be used on a lattice part. But you can certainly find cores like that from each of the fpga/cpld vendors, tuned for and likely free on their platforms. Plus what is it the 68hc11 there are free and or for purchase cores, probably 8051s, etc. And of course there is the cortex-m1, not open but if you wanted a microcontroller in source form to implement on your platform.
The propeller is probably the closest to what you are looking for.