Gmail
You can check any Webmail on the Chromebook, but if you're a Gmail user, you can expect tight integration between your email and the browser. Google employees are already using an offline version of Gmail internally, and it will be ready for all Chrome/Gmail users sometime this summer -- at some point after the June 15 Chromebook release date. Gmail offers a lot more than just email -- you can do voice and video chat right within the browser.
