Those looking for more evidence that Apple is planning to update their Mac notebooks need to look no further than the Mac App Store. Astute users have noticed that a Mac App Store tool called FolderWatch was updated today to include support for what the developer calls Retina graphics.

Apple is reportedly planning to update their 15-inch MacBook Pro as well as the 11-inch and 13-inch MacBook Air systems at WWDC next week. All of the systems are expected to get the Retina display treatment as per previous reports.

In April, Intel said that Retina-quality displays were coming to notebooks and desktops as early as next year. While this doesn't specifically apply to Apple's Mac line, it's an indication of where they think the market is heading in general.

More specific hints about the MacBook line surfaced last month when some questionable benchmarks showed up on Geekbench. One result detailed a quad-core Core i7-3820QM, an Ivy Bridge CPU. 9to5Mac also got word from a reliable source that the new system would have a Retina display.

The Next Web notes that it would be easy for a developer to include a reference to a Retina display in an update but further points out that Apple would have had to approve it before it went live. It could have been an oversight on Cupertino's part or perhaps they are alright with it. Furthermore, the publication points out that Folderwatch was featured as an Apple Staff Favorite app in June 2011. Perhaps this award granted them early access to confidential information.