Looks like a more accessible front-end client for IRC - this is awesome. I love using IRC for communication and this just makes it an easier sell on less technical colleagues.

I hope that the Slack service supports using your own IRC client as well. That would be the bees knees.

You can use IRC with Slack. Once you sign up go to https://my.slack.com/account/gateways

"The Slack founder said he doesn’t track things like installs or signups because those metrics are “bogus,”"

LOL this guy is full of shit. He has 4 tracking codes just on his website.

Aren't people done trying to kill email?

The most fascinating part of Slack is that it's following a similar path to that of Flickr. A game which didn't pan out followed by a pivot to a social/collaboration service.