New rumors point out that Apple is planning to unveil a revamped Apple TV at the iPad 3 (or iPad HD) unveiling event tomorrow in San Francisco, California. The Verge reports that Apple has chosen to unveil their TV product at the iPad event because the two products share the same chipset.
A source told The Verge that the chip used for the new iPad and the new Apple TV is the rumored A5X, instead of the expected A6 - the former being a quad-core successor to the A5 series. Another source has also confirmed (this time to CNET) that the chip will still be dual-core, so it's likely to be the A5X.
The new Apple TV set-top box will have 1080p support and the AirPlay mirroring feature which works with the iPad 2, the new (unreleased) iPad and the iPhone 4S. Up to now, Apple TV had a 720p limitation, which made sense since Apple Store never had Full HD 1080p content available for purchase.