Google is probably tweaking all Google Apps interfaces to have an unified interface inspired from the Google wave’s interface. Google Apps interfaces are not pretty, the recently hyped and still in invite only beta does look better and many users liked that. According to Engadget Google apps will have interface similar to Google Wave.
The screenshots came from an anonymous tipster to Engadget, so for the moment this is not confirmed and it is just a rumor.
Specifically, we’re told that “the goal is to provide a consistent experience throughout all Google Apps and blur the line between the browser and the website (e.g. drag and drop, right-click, etc.).” (Via Engadget)