Here’s a preview of the Atari Flashback 2.0 system which can be hacked to play original cartridges. This will be a great source of new hardware for Atari 2600 fans. Even says it implements the entire 2600 on a single chip. If you read the entire article it looks like you could make a portable Atari out of this, make game switcher (internal / cartridge) and more. Thanks Robert!Link.
Atari Flashback 2.0 Preview