New Steam Mobile App

Valve announces the availability of an updated Steam Mobile App for iPhone and Android. This includes two-factor authentication for your Steam account, store and library access, customizable notifications, and more. Here's a new video showing off all that's new. Here's a summary:
We've completely revamped the Steam Mobile app - with a new framework, new design, and new features. You’ll still be able to browse the store, get Steam Guard codes, and confirm trades - with additions like QR code scanning for PC sign in, smarter notifications, customizable tabs, and a new Library view with remote downloads.

Supported by work across the entire Steam platform to improve account security, including new sign in experiences on the web and in the Steam Client, the mobile app is the best way to keep your account secure with two-factor authentication.