As with anything it's horses for courses. Apps are always going to be able to do things that the web can't. Or, rather, do it much slicker.
Take the iPad's Twitter app. It's amazingly rich and fluid. A pleasure to use. They tried to do something similar with the "new Twitter" site. Doesn't (can't?) even come close though.
A web app is never going to be as rich or as natural-feeling as a native app.
As with anything it's horses for courses. Apps are always going to be able to do things that the web can't. Or, rather, do it much slicker.
Take the iPad's Twitter app. It's amazingly rich and fluid. A pleasure to use. They tried to do something similar with the "new Twitter" site. Doesn't (can't?) even come close though.
A web app is never going to be as rich or as natural-feeling as a native app.
A Notes-based mobile OS? Erk ;-)