OS X users digging through Thursday's beta update to the system have discovered what appears to be a reference to an as-of-yet unannounced version of the iMac. The model, dubbed iMac 15,1 could be shown off next week at Apple’s WWDC conference, where we’ve heard that there will likely be some new hardware announcements. The 15,1 designation refers to a model that doesn’t exist yet (as the current-generation iMacs are designated 14,1 and 14,2 based on display size). Whether we’ll see any other hardware at next week’s conference is still unknown, but there don’t seem to be any other unreleased models included in the 10.9.4 update. The fact that the machine is included here means that it will likley see a release soon, possibly even the same day as the WWDC keynote.