I was in fact writing this article as the code was downloading.
I have written in the past about making WLW portable as well as about the first rumour on open sourcing this tool. It turns out that rumour was true!
It turns out that Open Live Writer is not yet at full parity with Windows Live Writer, as portions of the code could not be made freely available. Fortunately, what is not available yet does not seem difficult to replace.
More importantly, there is talk about adding functionality (tumblr) as well as porting it to MacOS as well as Linux.
A weird side-effect of installing the new tool is that after install, I can no longer use my old WLW 2012 portable to post to Blogger.