The report comes from Re/code, which says that the company will be unveiling the "latest updates to its iPad line." That likely means the iPad Air 2 (or, if you prefer, 6th-gen iPad) and 3rd-gen iPad mini. The new tablets are rumored to receive Touch ID fingerprint sensors and faster A8 processors.
The report also supports 9to5Mac's report that the event will include an iMac with Retina Display. An iMac with a 4K or 5K screen would be Apple's first high-resolution desktop PC.
Apple will also be revealing OS X Yosemite, the latest version of the Mac's operating system. Announced in June, the update gives OS X a flat-design makeover, along with iPhone syncing (Handoff), improved Spotlight search and iCloud Drive.