WordPress.com have added a Turbo button in the admin area. This is to enable Google Gears, if your browser supports it, and speed up things using it. For instance, Google Gears is used for offline access to web apps like Google Docs.On WordPress.com it is used to store all images and other web page components from the admin area to the user’s PC, speeding up access and reducing unnecessary web traffic.WordPress 2.6, will have the same kind of support for Google Gears.
Google Gears is a browser add-on from Google that enables web applications such as Google Reader and Google Docs to feel more like an offline application like MS Word or Excel.It does this by storing information on your machine allowing you to read, edit and update “data” from the internet without actually being connected. And then, the next time you connect to the internet it synchronises with the website, uploading any changes you’ve made, and downloading any changes/updates that have been made on the site.