MacRumors has discovered a new Safari feature that will compete with Instapaper and ReadItLater in the latest Mac OS X Lion Developer build. The feature, called Reading List, allows users to save web pages for later reading. It's represented in the toolbar by the eyeglasses icon to the right. Currently the feature is inactive, but Apple does offer a description of it:
"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."
As MacRumors points out, Apple's implementation looks to be partly based on HTML/js, which off the bat wouldn't allow for synchronization between devices. However, if Apple plans on adding the popular functions of services like Instapaper and ReadItLater into Safari, it's very likely that they will add syncing features as Safari for Mac OS X and iOS are tightly integrated. The image below shows you how items will be displayed in your Reading List.
Apple OS X Yosemite