Inside OS X 10.8 Mountain Lion GM: Safari 6 adds iPad-style iCloud-shared tabs
New notification settings
Apple previously added a variety of new options related to passwords, privacy settings, and Notification Center support for websites. In Safari 6, Notifications gets its own pane in Safari Preferences, which lists the websites that "have asked permission to show alerts in Notification Center."
The new feature will allow web developers to post updates (if the user gives permissions) just like a local app, putting web apps and other cloud based services in this regard on the same footing as native local apps. Safari preferences still uses the same older-style notifications icon that currently appears in System Preferences; it may be that this will be replaced with the new icon now being used in Notification Center.
As Safari previously noted in earlier builds, "a website that is allowed in Notification Center can only send you alerts when it is open in Safari."
New preferences pane for passwords, privacy
Mountain Lion's Safari 6 preferences provide a new Passwords browser for finding and recovering (or removing) saved passwords you've entered on websites. This works similar to Keychain on a system level. From Safari's Preferences, the Password pane presents a list of the sites you've saved a password, the user names you've entered, and the passwords (revealing them requires entering your system password).
Safari 6 also makes some subtle changes in how it presents privacy options. Safari is still set by default to "block cookies from third parties and advertisers," (the feature Google got in trouble for bypassing) although the preferences Privacy pane (shown below) now offers to "ask websites not to track me" rather than wording the "Do Not Track" option as "tell websites not track me."
Do Not Track is a feature that has been added to all browsers apart from Google's Chrome, and currently only "requests" that web servers not track the user returning it. Wikipedia notes that "websites are not legally required to comply with do not track requests, neither by law nor by broad social consensus, and therefore very few websites recognize and respect this privacy signal."
Apple has also changed the setting for "allow search engine to provide suggestions" (set on by default) to the more active sounding "prevent search engine providing suggestions," and option that is turned off by default.
Removed RSS, Offline Reading List and other options
Safari (along with the new Mail) erases RSS as a tacked on feature. The RSS reader features in both Mail and Safari were rather bare bones, making a standalone RSS client more attractive for most users. With RSS removed from Safari, it's not clear whether Apple is just backing out of RSS reader support or if (perhaps more likely) it is gearing up to release a standalone new RSS reader of its own, perhaps tied into Podcasting and other applications of RSS.
Safari 6 has also added an offline reading list feature, enabling users to read sites added to the Reading List even when not connected to the Internet. Safari automatically presents Reading List as an option when it can't connect to the network.
Other features missing or changed in Safari include the Standard and fixed-width font selections under Appearance (the entire pane is simply no longer there in preferences) as well as the Security pane option to "ask before sending a non-secure form from a secure website," which appears to have been made the default behavior.
The Advanced pane removed an option for database storage size selection (for HTML5's "super cookies"), but now ads a default encoding option for text. Additionally, in Safari 6 the option to "Block popup windows" has been restored after going missing in some developer builds.