With Apple’s WWDC 2012 keynote a tantalizing four days away, recent rumors about the updates for Apple Mac line have gotten a major boost today. The centerpiece of those rumors is the MacBook Pro, iMac and MacBook Air would be getting a retina display. Today, Apple gave as much confirmation of those rumors as we’re likely to get before Tim Cook takes the stage on Monday. It seems that sometime yesterday evening Apple approved the first ever retina display-read app for the Mac App Store.

The app in question is called FolderWatch, a handy backup utility that syncs the contents of a folder on your Mac’s hard drive with another folder (e.g., a backup folder on an external drive). Last night the app’s developer tweeted that the new update (version 2.0.4) had been approved by Apple:

Here’s the list of changes from the app’s page in the Mac App Store:

The interesting question, of course, is whether Brothers Roloff made the change based on any inside knowledge about what Apple has coming up, and what exactly they mean by “retina graphics.” That is, has Apple been cluing developers in on the fact that Macs are about to get retina display? Brothers Roloff has not yet returned a request for comment sent via Twitter, but when asked by another Twitter user about what they mean by retina graphics, they said that it refers to a HiDPI display:

There have been references found in OS X Lion to HiDPI mode, a resolution setting apparently designed to accommodate extremely high-res displays. That is to say, displays with higher resolution than anything Apple currently has on offer. The new version of FrontWatch, then appears to be designed to run on those HiDPI displays.

Finally, it’s worth noting that whether Brothers Roloff are operating with inside information or anticipating the rumors, the fact remains that Apple approved the app with the reference to “retina graphics” in the description. While that doesn’t quite constitute confirmation that the next Macs will have retina displays, it’s a pretty good clue.