Future versions of Firefox are to get a new tab organisation feature called Tab Candy. The feature, which resembles exposé from Mac OS X, allows users to easily group and organise tabs into groups.
“With one keystroke Tab Candy shows an overview of all tabs to allow you to quickly locate and switch between them. Tab Candy also lets you group tabs to organize your work flow. You can create a group for your vacation, work, recipes, games and social sites, however it makes sense to you to group tabs. When you switch to a grouped tab only the relevant tabs are shown in the tab bar, which helps you focus on what you want” wrote Mozilla’s Aza Raskin.
Available as an alpha build, Tab Candy is written solely with HTML, CSS and JavaScript, meaning there is no native code for any platform.
More details on the project can be found in the Mozilla Wiki, while an alpha preview can be downloaded form the Mozilla FTP.