The iPhone SDK (software development kit) made available yesterday includes a new version of Dashcode (v. 2.0 Beta ) that allows creation of Web apps for the iPhone. When you click run, these Web apps launch in the Aspen Simulator. The tool also has support for bundling home icon images into the deployed Web app.
Preset styles include the standard sliding-style "Browser" interface. Code snippets include gauges, indicators, forward and back buttons, form elements and more.
Whether this means Web apps will be able to be stored locally under iPhone software/firmware 2.0 has not yet been determined.
[Thanks to iPhone Atlas reader Patryk Laurent for pointing this out]