At http://nodejs.org/#about it says the following:
"Node is similar in design to and influenced by systems like Ruby's Event Machine or Python's Twisted. Node takes the event model a bit further—it presents the event loop as a language construct instead of as a library."
Are there other frameworks or languages that likewise expose the event loop?
Tcl has had this capability all along (last 2 decades). See http://www.tcl.tk/about/netserver.html
This is not to say Tcl does -- or should do -- everything Javascript and/or node.js does. But it is a valid answer to the question as to what "other frameworks or languages ... likewise expose the event loop?"