This looks neat. I guess it is better than having two separate windows… I guess.
Facetop is an experimental videoconferencing implementation that superimposes a ghost image of the person you're talking to over an image of their desktop, allowing you to not only communicate with them via video but to share control of applications, watching them make changes as they go. Although the system is just software, essentially, because it uses extensions built into OSX it is expected to remain Mac-only until Microsoft launches Longhorn in a couple of years (although it's likely that someone would be able code something similar in Windows if they wanted).
It might be important to point out that the people in these screen shots aren't reflections -- that's the output of Facetop.
Read - 'Facetop' Blends Screen and Video Images [RolandPiquepaille via CoolHunting]