Users of the Mac have been given an interesting amalgam of old and new, a combination of a traditional application and a webapp: Mailplane. It looks to be a wrapper for Gmail which mildly extends its functionality and desktop integrations, specifically in the areas of attachments and account management.
Webapps are great because they are on the web. The web also limits how much these webapps can be integrated with the desktop. Perhaps concocting a quick wrapper hybrid like this is the way forward? Perhaps not in the case of Gmail, where accessing your mail via a thirdparty email application using IMAP would be a smoother experience. Even so, I’d like to speculate that Google will be extending the base-functionality of Chrome, so that application shortcuts could mimic this behavior.