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.