The iPad Pro is rumored to be a 12.9-inch iPad that would appeal to professional, productivity users, similar to the iPhone 6 Plus in the phone lineup.
While early rumors pegged the iPad Pro's release for early 2015, production is now being rumored to start this fall, in the September time frame. No word on an Apple Pen this time around, though. According to Bloomberg says:
Production of the 12.9-inch-screen iPad is now scheduled to start around September because of delays involving the supply of display panels, said one of the people, who asked not to be identified because the details aren't public.
Apple has long been expected to reveal a larger version of the iPad in order to appeal to more niche markets in creative fields. However, no concrete details about the device have been nailed down yet. A 12.9-inch display has been rumored for a long time, but there have also been reports of a 12.2-inch device under the name iPad Air Plus. In any event, we likely have a while to go before any official announcement.
No such device has been announced by Apple, of course, which means any "delays" in any components would be part of an ongoing development cycle.