Google calls these messages "rich notifications," which makes sense given the usage of the term "rich media," favored by Adobe as a way to differentiate Flash content from the Web content, back before Web content caught up.
"Rich" isn't really a good adjective in this context because it's associated with monetary wealth at least as much as complexity. But presumably alternative nomenclature like "elaborate notifications" didn't quite roll off the tongue. And perhaps there's some truth in the terminology: "rich notifications" could conceivably cost more to create (in terms of developer time) than "poor notifications."
[ Google, among others, is trying to take advantage of Apple's shortcomings. Check out 7 Slick Siri Alternative Apps. ]
In a blog post for developers, Google software engineer Justin DeWitt said rich notifications are available in the latest Chrome for Windows beta, dev channel builds on ChromeOS, and will soon be available in Chrome for OS X and Linux.
"Rich notifications include full-bleed icons and space to convey a headline and short message," DeWitt said. "Additionally, they enable you to create action buttons and respond to clicks right within your app, empowering your users to do anything they could do within the app's UI itself."
Notifications that contain images and interactive buttons appear to have value as a way to improve the user experience, but they also represent encroachment on the operating system as the software layer that handles interaction outside of apps. That's not really unexpected given that Chrome OS is an operating system, but it may be surprising for those who still think of Google's Chrome browser is just another Web browser.
Google talks about Chrome OS and Chrome as though they're different products, but really they overlap significantly and they're continuing to converge. The major commercial operating system vendors, Apple and Microsoft, have long worried that Web technology has the potential to marginalize native operating systems and have taken steps to prevent that. But it may be too late, assuming neither Apple nor Microsoft wants to invite antitrust scrutiny.
The emergence of rich notifications is a relatively minor trespass on operating system territory. Chrome packaged apps represent a more substantial tour of the lawns maintained by Apple and Microsoft: They are Web apps that run outside the browser. They don't threaten OS X and Windows directly because computer users not using Chrome OS still need to boot into an operating system. But they're capable of handling so much user interaction that the underlying operating system becomes irrelevant: All roads lead to the Web.
The performance of Web apps, the clumsiness of Web app UI, offline functionality and network bandwidth have all limited the competitiveness of Web apps. But those issues are being resolved as Web technology marches onward.
On mobile devices, native apps have thrived at the expense of Web apps, but even there, the competition is closer than it appears. Web apps can compete with native apps in most circumstances if properly coded. And the discovery and monetization advantages of native apps have diminished as the supply of native apps has exploded. With an efficient distribution mechanism in the form of Web app stores and packaged app installation from websites, the Web can regain lost ground.
Chrome's rich notifications carry a message: The browser is the operating system.