Vivaldi has always been one of the more interesting of the Chromium-based browsers, in no small part thanks to its emphasis on building tools for power users in a privacy-centric package, but also because of its pedigree, with Opera's outspoken former CEO Jon von Tetzchner as its co-founder and CEO. Today, the Vivaldi team is launching version 4.0 of its browser and with that, it's introducing a slew of new features that, among many other things, include the beta of new built-in mail, calendar and RSS clients, as well as the launch of Vivaldi Translate, a privacy-friendly translation service hosted on the company's own servers and powered by Lingvanex.