This is not new, my packaged app has been in market for a long time now. The APIs are always developing. Such apps have been possible for some time now.
edit: to be precise, my app is almost a year old and the packaged app stuff was there even before that. And in chrome world, twelve months is a very long time.
It will launch in a window in chrome OS in the new interface. It is a packaged app as in all of it's resources are bundled in the crx and it does not need anything from the web.
The difference b/w this and old version is that it has access to more apis. The underlying idea of a packaged app (that all data is bundled in .crx file) is same for both of them. This is discussed here. http://code.google.com/chrome/extensions/trunk/apps/app_arch...
A shameless plug https://chrome.google.com/webstore/detail/fddboknafkepdchido...
edit: to be precise, my app is almost a year old and the packaged app stuff was there even before that. And in chrome world, twelve months is a very long time.