First impression: it looks very much like Slack and I don't see where it explains it is a combination of Slack and Skype? There's no mention of conference call and video call.
#2 is an interesting hack indeed. But from the demo video (posted in a different comment), it also works for attachment so I don't think he is using this method.
Edit: I signed up and you were right. He uses a remote image. It works when I email using the unsend.it web app but doesn't work if I send it through the Gmail website so I couldn't test the attachment.
I actually like my shell as it is. I like the old fashion with no mouse interaction except for scrolling. Is it just me? But I have to say the interactive search is appealing.
It does look simpler but could it be because there are less functionalities and it is less extensible? won't be enough to be called an alternative. I voted up though because I still think it's cool. Hope to see it grow further.