Google Chrome's development is high-paced and version numbers are not very significant, but it's weird to see a pre-beta release of Chrome 2.0, four months after Chrome 0.2. There are many new things in Chrome 2.0:
How to get the new version?
1. If you don't have Google Chrome, install it from google.com/chrome
2. Subscribe to the developer preview channel. This is required even if you've previously subscribed to the channel.
3. Wait until the new version is downloaded (you may force the updatie by opening the "About Google Chrome" dialog).