Evidence of Push Notifications for Mac has been found in the FaceTime Beta application, according to a 9to5Mac report.
A user informed the site that when using FaceTime for Mac, Little Snitch was tracking all kinds of unrecognized activity.
"Little Snitch told me from time to time that "apsd-ft" wants to establish a connection with an Apple server (for example 7-courier.push.apple.com). As far as I can see, apsd-ft stands for "Apple Push Service Daemon – FaceTime". So I dug a bit deeper. There are also some new launch agents in ~/Library/LaunchAgents like com.apple.apsd-ft.plist und com.apple.FTMonitor.plist."
Interestingly, Apple hints at Push Notifications for the app on their website.
Your Mac is ringing Whenever someone tries to reach you, the call rings through on every Mac you own even if FaceTime isn't running. So you never have to worry about making yourself available. If you don't want to receive calls, just turn FaceTime off in Preferences.
It's likely that Apple will enable Push Notifications for all the apps it sells in the upcoming App Store.