XMR as a payment method for OpenBazaar has been discussed several times. Personally I believe OB + XMR will be the killer combo that enables private, uncensorable, truly free trade.

I've discussed this in person with Brian Hoffmann from OB1 and he said he's happy for the Monero community to implement this, but can't commit OB1 developers to the task.

XMR for OB payments was discussed most recently in this reddit thread: https://www.reddit.com/r/Monero/comments/9jx1ne/openbazaar_is_looking_for_monero_integration/

"It would be awesome if someone from the Monero community, uh, contacted us to have us fully explain what is needed and they can go off and build it." https://youtu.be/Lt_3RdS30uk?t=39m42s

The purpose of this request is to (a) fund a dev to work with OB to scope out the needed changes, and then (b) go ahead and implement it.

Needless to say, I'm happy to be the first contributor if someone can pick up the ball and move it forward.