Check out the following link for a Xib to JS converter:
Just no time at the moment due to my day job, developing my own app, and enjoying family life!!
This would be a much sought-after product. I've done similar things to this in the past using other technologies.
Ideally, the product would be written in Titanium Desktop, and would have drag-and-drop UI objects. It would have a right-click property inspector for each object. The property inspector would have a list of all the possible properties for each object (with drop-down lists for options where applicable) and a list of possible events that can be handled.
It wouldn't have to be a full-blown Visual Studio, but could at least generate the basic objects and maybe the event handlers.