Apple has approved an update to Folderwatch for the Mac App Store, an app that lists “Retina graphics” as one of its improvements.

The Next Web reports that Folderwatch 2.0.4 was approved on Friday, indicating that today’s WWDC keynote could bring high-resolution Retina display Macs to Apple’s lineup.

In May, Apple appeared to begin preparing its operating systems for high resolution Macs. In an update to OS X 10.7 Lion, Apple increased the resolution of some of its application icons to ready them for Retina displays.

It is expected that Apple will announce Mac hardware updates this evening at Tim Cook’s keynote. These updates could be a new Mac Pro, new Air-like MacBook Pros, new MacBook Airs, and new iMacs.

To find out for sure, tune in to our live feed of Apple’s keynote at WWDC tonight at 6.00pm here.

It looks like Apple will also be unveiling iOS 6 at the event, after banners for the next-generation mobile operating system were spotted being put up in the Moscone Center, San Francisco, the venue for this year’s WWDC.