I don't think there was much. There were a couple grumpy tweets exchanged and blog posts written. But from reading Atwood's own posts on the subject, the timeline appears to run: complain Markdown needs a standard; learn Gruber isn't enthusiastic about that; work on a standard in secret for two years anyway; at the end of the two years let him know that you plan to release it (and I'm really curious what was said here, because if he'd said no after they'd put in two years, what was the plan, exactly?); take his failure to respond to your (apparently single) email in two weeks as implicit permission; go ahead and do it anyway; propose a new slightly-changed name when a shitstorm erupts; take Gruber's failure to respond to email about the name change in a single day as implicit approval.

I'm down with the idea of developers getting together and forming a common standard for Markdown implementations if they want to do so, but Atwood & Company have consciously and deliberately thumbed their nose at Gruber through this whole process. They could have just called it "Plain Text Markup" and explained in the first paragraph that yes, it's Markdown with all the ambiguities taken out. Hell, they could have called it "PTM: The Standardized Markdown Specification." They could have even called it "Pandoc-Flavored Markdown," which AFAICT is (mostly) what it is. But "Standard Markdown" came across as we are taking control of Markdown over your objections and the way they developed and announced it greatly amplifies that reading. I'm not convinced "Common Markdown" is much of an improvement, and the "Well, we're pretty sure this will make John happy even though we didn't actually wait for his response" definitely doesn't help.