Widgets may well allow for flexible UI and deployment options and are a W3C standard.
Wookie is widget server that OSS Watch are working with and is not in the Apache incubator.

http://getwookie.org/Welcome.html
http://osswatch.jiscinvolve.org/2009/07/17/wookie-accepted-into-apache-incubator/

Wookie is a Java server application that allows you to upload and
deploy widgets for your applications. Wookie is based on the W3C
Widgets specification, but widgets can also be included that use
extended APIs such as Google Wave Gadgets and OpenSocial.

= Background =

The [http://www.w3.org/TR/widgets-reqs/ W3C defines widgets] as:

''Small client-side Web applications for displaying and updating
remote data, that are packaged in a way to allow a single download and
installation on a client machine, mobile phone, or mobile Internet
device. Typical examples of widgets include clocks, CPU gauges, sticky
notes, battery-life indicators, games, and those that make use of Web
services, like weather forecasters, news readers, email checkers,
photo albums and currency converters.''

The Widgets v1.0 working draft targets platforms such as Apple
Dashboard, Microsoft Sidebar, Yahoo! Konfabulator, and mobile
platforms such as WidSets. Web widgets, such as Google Gadgets, are
not currently in scope for the specification, although when you dig
into the details of the specification, its obvious that web widgets
can potentially be developed in a similar manner. For example, the
OpenSocial API is an example of an extended Web Widget API - in this
case to enable Widgets to access things like friends lists and status
information.

Widgets are intended to be embedded into other applications in order
to provide a customised user experience on a variety of platforms and
form factors. A widget will therefore typically consist of Javascript,
HTML and CSS.