I wouldn't call those directly equivalent, although they are in the same space.
One of things Mojito is supposed to do is allow progressive enhancement (for performance, etc) by allowing you to define how much rendering takes place on the client and how much on the server.
That's what I gleaned too; maybe "alternative" would have been a better choice than "counterpart".
In one of my recent projects I used EJS and DNode to fairly easily implement a system for determining where the rendering takes place. I don't have anything to monitor connection quality & client capabilities though, so Mojito may prove useful when it matures.
DNode is about Node APIs on the client, where as YUI is about x-client code. As such I'm assuming moving YUI based rendering back is a lot more x-client compatible than using DNode to mimic Node's I/O interfaces.
I think my point is that sharing JavaScript isn't the biggest challenge in this space. Having a cross-browser rendering system that also runs effectively in Node is.
While you could use DNode to make that, I'm wondering if it would be nearly as robust as what they are trying to do.
One of things Mojito is supposed to do is allow progressive enhancement (for performance, etc) by allowing you to define how much rendering takes place on the client and how much on the server.