Firefox has a presence on most operating systems (Mac, Windows, Linux, Android and iOS), so the goal would be that a website could send you a notification whenever and Mozilla would figure out the best place to alert you of it.
(Disclaimer: Mozilla employee, but not working on notifications)
http://jbalogh.me/2012/01/30/push-notifications/
And, the wiki page:
https://wiki.mozilla.org/Services/Notifications/Push/API
Firefox has a presence on most operating systems (Mac, Windows, Linux, Android and iOS), so the goal would be that a website could send you a notification whenever and Mozilla would figure out the best place to alert you of it.
(Disclaimer: Mozilla employee, but not working on notifications)