OK, fair enough, but is it really extensible? Can you substitute the weak overlapping notification popups with something else, like growl on the Mac? Can you even change the beep?

If not... developers won't use it.

Same question. Does it work? Is there a way to make a plugin for any system that provides a complementary API? If so, what's going on? Why is it not in use?

If Nokia gets some legs under these initiatives... the PIM whiners (of which I am the self-proclaimed crown prince) might quiet down.

A little.