If you have experience developing native applications and games for mobile telephones then you probably already know the difficulties in developing different versions of the same application for the different platforms and for the different phone models.
The possibility to develop a web application surely exists. Yet, when doing so, in most cases, we are still limited when trying to use the device native special capabilities (e.g. sensors, camera etc). The solution for this limitation can be developing an hybrid application, which is a natvie application that includes a web browser user interface component that renders the application user interface, executes most of its logic implemented in java script and interacts with the native part of the application for getting access to the device native special capabilities (e.g. sensors, camera etc).
Whether you aim for developing a mobile web application or a mobile hybrid application you will surely be happy to know about jQuery Mobile, a touch optimized web framework for smartphones and tablets.
More info about this new framework can be found at www.jquerymobile.com.
The following screenshots (were taken from jQuery Mobile web site) present some of the planned user interface component for mobile telephones.
The following screenshots (were taken from jQuery Mobile web site) present some of the planned user interface component for tablets.
The first release is scheduled for late 2010.