Rumors are swishing around the grape vine (having originated on the Think Secret rumor website) that Apple may be hatching a secret plan to release its next iteration of Mac OS X, Leopard, in June.

Now before you go throwing a bucket of cold water on the story, you do remember that the iPhone is slated to debut in June, possibly even June 11. Apple CEO Steve Jobs told attendees at last year’s Worldwide Developers Conference that Leopard would be on store shelves in the spring of 2007, and summer does fall on June 21. If a mid-June rollout is in the cards for Leopard that doesn’t give much time for Apple to get the word out and start building some hype before the iPhone steals all of the attention.

Apple hasn’t confirmed all of the features that Leopard will have, but we do know some of the nifty things it will supposedly be able to do. OS X v10.5 users will get the ability to install Microsoft’s XP or Vista on Macs that have Intel-based processors separate from the Apple OS, allowing them the ability to have a PC and Mac under one computer chassis.

Leopard customers also get a new program that restores any file that previously existed on their computer (the app is called Time Machine), have multiple desktops with different looks and applications, a next gen animation routine (Core Animation), enhanced web tools, iChat programs and native support for all 64-bit applications. There will probably be some more bells and whistles in Leopard but until Steve decides to share his plan with the rest of us, the rumors will continue to swirl around.