With the increasing popularity of smartphones and tablet-PCs it's also important for RAP to support and adapt to these platforms. RAP can offer powerful solutions for such scenarios, allowing to write complex business-applications for modern mobile devices, provided a appropriately fast internet-connection is constantly available.
There is a common look and feel, as well as certain features, that most mobile applications have in common, even across different platforms. The RAP web client can conform to those within limits, but it is mostly up to the application developer to imitate these patterns. It is also recommended to create a custom theme or theme-contribution when targeting a mobile platform to accommodate to for the smaller screens and less precise aiming. This also allows hiding the rap-scrollbars (by setting width to 0), which are uncommon on mobile UIs. On the other hand they may be useful for scrolling across larger areas, but should then be wide enough to hit with a finger.
As of RAP 1.5, support for iOs is mostly solid, while Android still has some more severe issues. This is partially due to some bugs of its default browser that are hard to work around. Most significantly, touch-scrolling is not enabled. It is recommended to avoid using ScrolledComposite when targeting Android and use a paging pattern instead. Touch-scrolling for Tree and Table will be added in 2.0 (Kepler).
Other devices have not been tested.
Due to emerging alternatives, further improving the default clients support for mobile browser is currently not a main focus of RAP development.
An overview of mobile-related bugs can be found in bugzilla.