It's been a bit silent in this area. Development stalled for a few weeks, then @ianm continued some work on the SEO side of things; like descriptions based on first post content.
I've been reconsidering the implementation with the graph images and will probably refactor everything. Right now there's a pretty complex solution to allow customization of the graph image which I dislike. It uses gd to generate every block of the image using very low level code. I'm hoping to implement another method of generating these images based off of a simple blade template and then capturing the generated HTML using a headless browser.
We cannot provide any ETA on this extension, but we'll do our best to keep you posted on our progress.