I just attended a talk by Seth Ladd from Google at RefreshSD. The first part was a general overview of new technologies associated with HTML5, including the new markup, CSS 3, offline storage, websockets, etc. None of that was news to me, but the second half, about the Chrome Web Store, was new and awesome.
The store allows developers to add their web applications for other people to install and use easily. It even includes a payment and licensing system that allows developers to charge for their apps. If you use Google Chrome as your browser, the store is easier to use through the tight integrations with the browser. Since all the apps are web-based, it's perfectly possible to browse the store and use the apps in other modern browsers, though the experience is not ideal.
I expect that it won't be long before we see Apple, Microsoft, and possibly other big tech companies creating their own equivalents of the Chrome Web Store. I'm curious to see how interoperability between them will play out. Obviously the web apps themselves will be usable in multiple browsers, but I'm hoping it will be easy to register the same app with multiple stores, giving the user the option which they prefer for installation and payment. Seth imagines that, in the future, web apps will identify themselves with Open Graph style data in meta tags, allowing auto discovery for inclusion in multiple stores.
This is an exciting development in the web for me, since the explosive success of Apple's App Store(s) has largely excluded web apps. Now those of us who are not interested in Objective-C or Java development can really start to get in on the fun.