Pluginweb.Net

Ryan Paul has written about creating rich Internet applications on Linux with WebKit:

The open-source WebKit HTML rendering engine is rapidly gaining ground on the Linux platform where it is increasingly being adopted by conventional desktop applications for content display. Ongoing efforts to facilitate tighter WebKit integration are opening the door for developing rich Internet applications on Linux with the open-source GTK and Qt development toolkits.

The article talks about the HTML 5 video support in GTKWebkit, using Epiphony, Maemo, and OLPC.