It is always good to know the cons and pros of tools we are using before starting a new project with them in order not to be disappointed later on.

A frequently-updated chart by Markus Falk does this for the mobile frameworks as there is a detailed comparison of their capabilities.

The chart displays the rendering engines supported, target platform, hardware, development languages, UI features and license for each framework.

Also, if you already have strict requirements for the project, a wizard helps filtering the frameworks and fastens the process of choosing the right one.

Jo is an open source mobile application framework that is based on HTML5 .

It enables you to create for multiple platforms like webOS, iOS, Android, Symbian, Safari, Chrome and Dashboard Widgets.

The framework is small in size, ~8kb, without any dependencies and compatible with many other JS frameworks.

Jo is also compatible with PhoneGap and makes possible to create native apps besides web apps.

It is very well-documented and has sample codes on every level.

Rhodes is an open source framework for building native applications for all major smartphone operating systems: iPhone, Windows Mobile, RIM, Symbian and Android using Ruby as the development language.

It has access to native device capabilities such as GPS geolocation, PIM contact reading/writing and camera image capture.

Development process can be called as "easier" with Rhodes as most of your UI customization can be done in HTML templates.

There are integrated styling libraries for matching the look and feel of native applications (ex: for iPhone, it is based on iUI and jQTouch can be used as well).