We're finally releasing Jolt Alpha – the world's fastest zkVM.

Jolt is fully open source. Always has been and always will be.

zkVMs are the closest I've seen to algorithmic magic and I believe they'll allow us to deliver on the promises of web3.

Building a new economy for Open Source at Merit Systems. 

Prev @a16zcrypto. 

Did my time in big tech, since recovered.

Is it targeting some standard ISA for the VM, or did someone over there build a whole new rust compiler target for a custom ISA?

No new compiler target or custom ISA. Jolt targets RV32I due to the relatively small instruction count. There is a small constant engineering cost per instruction.