I tried to look around, but... I can't find any general information what is this all about? Nodes? SmartMachines? There's loads of installation instructions, API docs, etc. but where is the "what is it and why should I care" page?
Regarding specs of the service offered, it just says: I need more memory or disk! "As part of our beta service we have one size Node Smart Machine available. In our tests so far, few developers have hit those limits. If you are running out of disk or memory send a message to support@joyent.com or try running Node on a standard SmartOS Smart Machine."
* It's designed around an event loop and non-blocking IO
* It executes server-side JavaScript on Google's V8 engine
* It's fast and high troughput
* Node.js is currently adopted by Joyent, Heroku, Yahoo and many others
And yes, both provide early beta hosted Node.js.
Heroku use their current infrastructure and offer node.js dynos on their new Beech stack. It's easy and fun to use.
Joyent offers a full VPS based on SunOS. It can host node.js and other supporting packages, databases, all freely installable. You can even ssh into a SmartEngine. Ryan Dahl, the creator of node.js, has joined Joyent.