Salesforce Chatter gives you an installable app for collaborating with coworkers over Chatter. You can access Chatter feeds and posting functionality with the power of a downloadable app.
You can launch the full Salesforce site directly from the app without authenticating again. Authenticating once saves valuable time so you can get back to work and access the Salesforce data you need faster.
You can also post drawings and notes made with a stylus directly to colleagues and in your Chatter feed on touch enabled Windows devices.