WebRTC client works on Chrome OS, too.
A new Skype for Linux client is now available as an alpha.

The Skype client for Linux had been long abandoned—it's stuck on version 4.3, compared to version 7 on Windows—but Microsoft has now belatedly recognized that Skype is at its most desirable when it's available on every platform. To that end, it has created an all-new Skype client.

The new client in fact has two versions. There's a Linux app for users of traditional Linux systems. There's also the Skype Web Client, which is supported in Chrome on Linux and Chromebooks running Chrome OS. Whether using the Web or the standalone app, the core code and capabilities are the same: it's using Chrome's WebRTC support to provide a plugin-free, Web-based Skype client.

At the moment this client is subject to certain restrictions. Skype is upgrading its network infrastructure, and the new Linux client can only make voice calls. It is also limited to people running the current version of the client on Windows, OS X, iOS, and Android. Communication with the old Linux client isn't supported. Nor, for the time being, is calling to landlines or mobiles. The new client is truly an alpha, and as such is not close to feature complete yet, but with common code being used for the browser-based client, too, progress should be relatively quick. The common code should also mean that this time around, Linux doesn't end up getting dropped and ignored—Web usage is too important to let that happen.