A webapp is not a replacement for a desktop app. There are very legitimate reasons for wanting a desktop app, more for some types of apps than others.
The approach we took is native for mobile and webapp for everything else.
Our users are asking for a "desktop app", so we are looking at wrapping our webapp in a SSB and distributing that.
Check out their whitepaper "Qt Cross-Platform Application Framework": http://qt.nokia.com/files/pdf/qt-4.4-whitepaper