This is an atmega328P chip pre-programmed with the Official Arduino bootloader.
This chip + bootloader is supported by the official Arduino 0013 release.
Arduino sketch capacity:
- 30K flash memory
- 2K RAM
- 1K EEPROM
The Arduino team also upgraded the upload speed, from 19200 baud on the atmega168 to 57600 baud on this new atmega328P chip.