updated 12:52 pm EDT, Mon June 2, 2014
Full info coming within an hour
A photo posted on Twitter (below) by reporter Lance Ulanoff includes two iMacs that appear to be running the next version of OS X, which may be called Yosemite. Very little of the OS is visible except for a new wallpaper. Apple will reveal more information about the OS during its WWDC 2014 keynote.