Btw. did you see vines? the ruby xmpp server? Sounds also interesting :)
Another thing, the fact that you're blocking JS may counter the "you're running it" example, but as you know, it doesn't invalidate the point that JS in one of the most used languages.
And X is way more fast/scalable/mature/secure than Twisted and Event Machine for some values of X I'm sure, yet Twisted and Event Machine are still worthwhile and useful things.
Also, the 2 lines are actually different. The node.js lib for redis is a bit weird, so we need both a "pub" client and a "sub" client :)