Techcrunch has confirmed it.

http://techcrunch.com/2013/01/25/rabois-left-square-over-sex...

Please forgive me if I don't count coverage by Techcrunch as verification. Did he tweet it? Link from FB? Send a signed email?

It could be legit, but the bar should be higher than this.

Kara Swisher says she got the same statement from him.

http://allthingsd.com/20130125/keith-rabois-long-statement-o...

I totally agree that most news sites do a poor job of verifying information before parroting information, but several sites are quoting a statement from Square that seems to verify this (e.g. http://www.latimes.com/business/technology/la-fi-tn-square-e...)

Every tech site is referencing it.

Wasn't there a post yesterday about how gaming sites reference sources because others do (without any due diligence)?

That's true, but Kara usually does a pretty good job of actual journalism and verifying sources.

Confirmed that he resigned is not the same as confirming he wrote the blog post.

"Rabois has written an emotional post about the situation on his personal Tumblr. Here’s an excerpt:" - Techcrunch

That tells us nothing, except that TC copy and pasted some content off a blog. Unless they're quoting an email from Square or Keith that at least confirms its his blog (they are not), then it's perfectly reasonable to be skeptical here.

Ah sorry, I must have missed that quote, but how does that connect to THAT blog?

[edit to add the question]

There are many tweets at https://twitter.com/rabois that seem to indirectly acknowledge authorship of "the message". People sent him tweets of encouragement based on this article, and he is replying with a variation of "thanks" to many of them.