During his keynote presentation at OSCON last year, Ubuntu founder Mark Shuttleworth described application extensibility as an important enabler of innovation and user empowerment.
Citing the Firefox web browser and its rich ecosystem of add-ons as an example, Shuttleworth suggested that the Linux community could deliver a lot of extra value by making scriptable automation and plugin capabilities available pervasively across the entire desktop stack.
The concept is very compelling and has a long history. There are many examples from which to draw inspiration, because similar capabilities are present in virtually every platform. Long ago, scripting languages called Guile and Tcl were the dominant extension languages of the Linux platform. Although both still exist today, they are somewhat anachronistic and are no longer widely used.
http://www.linuxlinks.com/portal/news/article.php?story=20090120141336167