Several have asked about node.js in contrast to io.js. It's fair to say that the emphasis of node.js at this point is on stability (including API stability, production debuggability/observability, etc.) and performance -- in that order. It definitely takes longer to release software when operating under these constraints; as the team writes in the linked blog entry:

We are also pleased to report that this release of Node.js has tests passing on all of our supported platforms. On the one hand, this seems obvious (what are tests for if not to verify before you release it?!), but this is actually the first release of Node.js that has operated under this constraint. Requiring that all tests pass before releasing Node.js marks an important development for the project, and is essential for building a solid path moving forward.

It's unclear what the divergence will be in the future, but the emphasis of the node.js team on stability may or may not be shared by io.js -- and in particular, this may be reflected in things like the V8 version, changes in which tend to subtly break esoteric things on different platforms. Inasmuch as the divergence represents different operating principles (i.e., enterprise-grade stability vs. bleeding edge), it may well be helpful -- and I think it's entirely conceivable that the projects will develop a symbiotic relationship moving forward.