Space Replay is a project by Francesco Tacchini, a Royal College of Art grad student, and Julinka Ebhardt and Will Yates-Johnson of Design Products:

A hovering object that explores and manipulates transitional public spaces with particular acoustic properties. By constantly recording and replaying these ambient sounds, the levitating sphere produces a delayed echo of human activity.

It’s equipped with a battery-powered Arduino — an Adafruit Wave Shield  in order to record and playback audio on-the-fly through  a small speaker. In the video below you can see how it moves around:

It actually reminds me of Rover, the large white inflatable balloon protagonist  of  the 60s sci-fi series the Prisoner! What do you think?