Yep...and if you use it for that it's brilliant.
My latest project runs Python/Pyramid and MongoDB for the more traditional computational stuff. We have a notification architecture running through node.js/socket.io sending real-time events down to the browser.
It works beautifully.
All of that COULD have been implemented within the Pyramid layer (or Twisted..or whatever), but it would have been much more difficult and time-consuming to do.