[ Thanks to kiterunner for this link.
]
“Apart from the aesthetic improvements like better polish and
beautiful new transparency effect, Unity Dash has some new feature
additions as well. The little icons you see at the bottom are
different Unity lenses (Apps, Files, a new Music lense and
Gwibber). Which means, there are no dedicated Unity lenses for Apps
and Files in launcher any more. The Ubuntu button(the one which
opens Dash) is now on the launcher and there is a new
minimise/maximise/close button for Unity dash also(see marked
regions of the above screenshot).”