It includes a 32K EEPROM where you can save high score data and stuff. I
think it would be cool if some of the past homebrews added support for
this. I'm going to do it with Marble Craze if I can find enough free space.
There's good technical documentation on the page and it includes some
easy-to-use code to get you working with the EEPROM (and speech
chip). They've included a specification of a system setup block that
currently includes TV information (PAL/NTSC/60Hz/50Hz) so you can
automatically set up your game accordingly. Pretty cool stuff.
I'm finally hammering out a new Atari 2600 music sequencing program (been
planning this for a long time) and I'm going to use the EEPROM to allow the
user to save sequences.