The main problem both systems have is that they're relatively immature. node.js is still undergoing heavy development, with a few breaking changes every couple of releases (although it's slowing down in that regard). And aleph basically just came out, right?
So I'd regard both as "things to watch" or bootstrapping solutions, not something I'd use for my Global Thermonuclear War management system.
I wrote Aleph this weekend, so yes, it's very new. However, right now it's just a few hundred lines around Netty, which is anything but immature.
I'm certainly not claiming it's flawless, or that there won't be any breaking changes in the future. However, I think this is a great example of one of Clojure's strengths: even brand new projects tend to have solid, well-tested foundations.
I agree. I had a similar problem with CouchDB a while ago when I tried to write the application in CouchDB. The interface was there, but it was obvious that some of the key features hadn't been implemented yet, requiring painful and complex workarounds. I went back to technologies I knew were tried and true.
If you're interested in playing around with tech and having fun, then these technologies are great. But for business I would avoid them for now.
So I'd regard both as "things to watch" or bootstrapping solutions, not something I'd use for my Global Thermonuclear War management system.