Due to the PS3's emulator not supporting all PS2 games, the first run of PS3's will include PS2 parts to ensure backward compatibility. Sony may remove the extra hardware after the first run of consoles, leaving the future of PS2 backward compatibility support in question.
According to an interview with Sony Computer Entertainment CEO Ken Kutaragi, the PS3's included Emotion Engine microprocessor and Graphics Synthesizer from the PS2 may not remain on the PS3 for long, despite the emulator's lack of support for some PS2 games. Sony's plan is to shift completely over to the emulator software that runs on a Cell processor once the software has matured.
Nikkei Electronics points out that there are 8,181 PS2 games that require backward compatibility support on the PS3. It remains to be seen if the emulator can cover them all the way PS2 chips can, potentially giving first-run PS3's some added value if the PS2 hardware is removed in later revisions.
Source: Nikkei Electronics