To join the various announcements from Adobe, MS, Dojo et al, here is Google Gears, a browser plugin and API (well, I believe 3 APIs) to enable online applications to work offline too. They are apparently working with Adobe to integrate with Flex but we need to see how all this shakes out in terms of standardisation. The plugin and SDK are released under BSD.
As always, what's the relevance to my project? Well, for one thing there's the changing nature of applications - where they reside, who has power over them, what they can do, how we maintain our identity in them. There are questions, as I say, related to standards or the need for them, and what their absence can mean for the long-term viability of applications built without them. And of course it's pretty cool tech.