I have been using this app for a while, it's pretty useful. It combines the private room aspect of services like Mumble/TS/Vent with the feature of giving a link to someone so they can do a one time join to the room. Good for friends and pick me up games. I like their persistent IRC-like chat-room too.
My group switched from Mumble to Discord and it's been such a great upgrade. I really am enjoying everything Discord has to offer so far.
Any chance for Linux prerelease?
Hey - Jason here from Discord. I'm one of the devs (and CEO). No pre-release Linux client but Discord does run in Chrome on Linux. A few features don't work there due to browser restrictions, like system wide push to talk.