Right now, all pages/web apps served from the same server have access to all each other's saved state of the same-origin policy.

@metromoxie is currently implementing a first version of per-page suborigins in Chrome, which should let the server isolate web app nodes from each other (by sending a unique string in the header for each one). http://www.chromium.org/developers/design-documents/per-page-suborigins