What happens when you have a web page, ASP page or WSH script with both VBScript and JScript? JScript and VBScript know nothing about each others garbage collection semantics. A VBScript program which gets a reference to a JScript object just sees another COM object. The same for a VBScript object passed to JScript. A circular reference between VBScript and JScript objects would not be broken and the memory would leak (until the engines were shut down). A noncircular reference will be freed when the object in question goes out of scope in both language (and the JS GC runs.)

the history of the IE6 Javascript GC, from the horse’s mouth

IE6 javascript GC is completely retarded. Microsoft has a patch, but does not distribute it via windows update. it is hard not to construe this as wanting to prevent web apps from encroaching on the windows / office franchise.