When the iPhone launched, one of the major gripes was the lack of support for native apps. Steve Jobs launched the web-apps-look-like-native-apps program, was roundly criticised for the lack of a native SDK, and sure enough it turned out it was already in the pipeline. The App-Age was born.
(Not long after, Palm released webOS, a web-app platform from inception, and it was roundly praised for its innovative approach.)
Circle back round a few years, and the plethora of native platforms (iOS, Android, RIM, webOS, WP7) and form factors (phone, tablet) combined with the emergence of HTML5 as a "standard" (albeit one implemented (in)differently by each platform developer) means that web-apps are now back in favour.
PhoneGap in particular seems to have captured the mindshare of the mobile developer community; it will be interesting to see how this battle plays out over the coming year. Gaming aside, once local storage becomes a common feature, web apps look unstoppable.