I was just checking up on ESP8266 support in the micro-python forums a day or so ago. I seem to have missed this.
I looked at the existing port, and a fork, about a month ago. I actually got a working repl over a serial connection, but found that documentation was lagging development and various APIs had been moved or renamed.
It looked like there was also a larger effort to refactor some of the micropython APIs to better accommodate differing hardware. It was originally created for the pyboard, but the recently shipped wipy, not to mention various community ports to other boards made it a pressing issue.
I'm glad there is a way to support the work.
Wonder how it stacks up to eLua (NodeMCU for esp8266). Python is a superior language, but I wonder if that will make MicroPython heavier than Lua.
The original proof of concept from fall of 2014 had ~24K heap available to user code. Not sure where it is now.