By publishing screenshots of a device or a software with the clock in that image posting to the next version of Android ,this clock gives the clue about Google's various Android releases. the company using this trick since the release of Gingerbread (v2.3).
The latest one is from Google's official Twitter account where the company posted screenshots of Google Now's new World cup info card. if you look , the time on the clock says 5:00 .
Even though Google is yet to announce the release date of Android 5.0 , according to some input it is most likely that the company will release it at the I/O 2014 conference and might name it Lollipop (though the name is not official yet).
Just after two weeks at Google's I/O , we will witness the release of Android 5.0 at the end of this month and the another one important announcements expected at the Google I/O is Android TV and might also focus on the Android wear.
Google has used following clock times for the various Android releases in the past :-
1. Gingerbread (Nexus S) 2:30
2. Honeycomb (Moto Xoom) 3:00
3. Icecream Sandwich (Galaxy Nexus) 4:00
4. KitKat (Nexus 5) 4:40