Its created by the one time Lead developer of vBulletin Keir Darby... its pretty new, about 6 months old I think. We use it.
Kier Darby and Mike Sullivan of vBulletin's new forum software. It's used for this forum here. I like it a whole lot and will definitely be using it for my next project!
Actually, it's not that old yet. It didn't go live on the company forum until the last couple of days in July so it's just about 4 months out now. But you're right about Kier Darby but also Mike Sullivan and Ashley Busby as well. It's only been available for use on the open market since Oct 5th.
People finally realise that vb does fail, and now they are almost freelance developers xenforo is so good.