Quite surprised. Exactly a year ago I was in hope that someone do something similar for Golang, but soon realized that it's impossible because Golang relies heavily on GC. Now this seems quite interesting.
Granted, ARM Cortex-M3 and NXP LPC2000 microcontrollers are more powerful than typical Arduino hardware, but one does not need to target all possible hardware out there.
http://technical.io/ even managed to run Node.JS on a Cortex-M3, but in the deeply-embedded world where performance/$ and real-time constraints matters, having a always-GC system like Golang (especially considering it's designed for cached cores) doesn't sound very promising.
However I did look Golang because it makes concurrency (quite important in embedded programming) easy. Now with Rust...
There are companies selling development kits with GC enabled system programming languages, like Oberon, for embedded development.
http://www.astrobe.com/default.htm
Granted, ARM Cortex-M3 and NXP LPC2000 microcontrollers are more powerful than typical Arduino hardware, but one does not need to target all possible hardware out there.