Apple is reported working on a new feature in the latest Mac OS X Lion builds called the "Safari Reading List," that will bring a different kind of bookmarking functionality to the browser. "Reading List" meant to offer users a way to save pages for later reading.
The new feature is described by Apple here:
Reading List lets you collect webpages and links for you to read later. To add the current page to your Reading List, click Add Page. You can also Shift-click a link to quickly add it to the list. To hide and show Reading List, click the Reading List icon (eyeglasses) in the bookmarks bar.
The concept is very simple. When you want to save a link for later, simply click shift and click the link and it will go into your reading list for later viewing:
To open up your reading list, simply click the reading glasses icon next to the bookmarks icon (not yet visible in Lion). You can also view saved links/articles in "reader mode" -- a feature that debuted with Safari 5 last year.
This feature is currently inactive and hidden within the latest Mac OS X Lion builds. Apple hasn't yet made any mention of the feature in any of their Mac OS X Lion documentation. The basic functionality would pit the feature directly against popular services such as Instapaper and ReadItLater. Apple's implementation appears to be partly based on HTML/js but it's not yet clear how robust a solution it will be. For example, one compelling feature of Instapaper and ReadItLater is the ability the synchronization of bookmarks across devices.