There are certainly features that are better suited for native apps, but the ones you stated aren't necessarily them. For example, GPS is doable on both Android and iPhone OS. Multitouch is also doable (check out Google Maps on the web on iPhone for an example here).

Accelerometer, native graphics, etc are the key features I think about that are not well suited for web apps.

My startup, AppStoreHQ (http://www.appstorehq.com), is a huge believer of mobile web apps, and we even have a private alpha going on for monetizing your mobile web app (check out an example like fortysquires: http://fortysquires.com ).