Apple is preparing to announce the iPad 3 on Wednesday, March 7, but cases for the third-generation tablet are already being shipped in sealed boxes to Best Buy.

According to an anonymous source reporting to PhoneArena.com, Best Buy has started receiving cases in sealed boxes with a sticker stating “Do not display until official iPad 3 launch.”

As third-party manufacturers are expecting Apple to start selling the new iPad soon after the official unveiling, cases for the iPad 3 are reportedly shipping in bulk ahead of Wednesday’s event.

“The shipment is not of just a few cases – there’s over 1,000 Targus Versavu 360 stands for the next-gen iPad shipping to Best Buy, meaning that it won’t be long until the actual tablet hits shelves,” stated the report.

The third-generation iPad will reportedly have a similar design to the current iPad 2, with a slightly thicker body due to a larger, more powerful battery, and edges a bit more tapered. Despite such minor adjustments to the design, Apple’s magnetic Smart Cover is expected to fit the iPad 3 as well.

The new tablet is rumored the same 9.7-inch display, however with a better resolution of 2048 x 1536 pixels, an upgraded A5X chip with higher clock speed and improved cameras.

Last week, a leaked picture showed that Best Buy’s inventory system listed “iPad 3” accessories scheduled to be in stock by March 11, further confirming rumors that third-party cases are being shipped to the retailer.

The official iPad 3 unveiling is expected to take place at the Yerba Buena Center for the Arts in San Francisco, California.