Google developers have wired up initial support for native Linux desktop notifications. This native platform bridge for Linux will communicate notification changes to the desktop environment via the D-Bus notification specification.
This native Linux desktop notification code is still being worked on, but once completed, will be used by default for Linux desktop environments that support notifications. Unity 7 though may be an exception as their notification system doesn't allow the use of buttons in notifications. In other cases, Chrome/Chromium on Linux will continue using notifications within the Chrome browser itself.
This support stems from a bug report issued last year requesting such native Linux desktop notification support.