So there's definitely a need for more lightweight contenders in this space.
Ideally someone would just do an "stb"-style JavaScript interpreter that would fit into a single .c or .h file. This is closer to that ethos than most other candidates, and as others have noted, Fabrice's credibility as a '1337 h4x0r gives it an instant leg up on the competition. I don't have an urgent need to switch away from V8 right now, but I'll be watching this project with moderate interest.
DukTape is already that.
Does the the application basically pass data to a user script (the user knows JS so it is useful for them?), and then the JS returns the data after processed?
Amusingly I asked the question and remembered that I actually worked on (supported) a hardware product that did this to some extent. It was a disaster as the scripting language would eat memory / cpu and crash the box ;)
What would someone....do with this?
Use it to run JS on some embedded device where you can run C?