We had some information to share yesterday about Android notifications in L, so you might have been having a bit of deja vu during the demo. Android L has a new stacked card style for the notifications using the Material Design interface. The features are also getting a boost in L.
Notifications on the lock screen and in the shade (they are actually merged in L) will be organized based on what Android thinks is most important, but it's fast to expand the full list too. A double-tap from the lock screen opens notifications, but what if you have a pattern or PIN lock? L's personal unlocking feature can learn about your environment and know if it's safe to unlock with a swipe or if the code should be required. For example, it can tether to your Android Wear device or remember your home WiFi. It will be faster to get at your content much of the time without sacrificing much in the way of security.
Those rumored heads-up banner notifications are happening too. They pop up at the top of the screen for important things like calls. You can act on them or swipe them away and get back to what you were doing. Presumably this is part of the smarter ordering of notifications to only bug you with pop-overs when necessary.