Yes but for starters, the AF unit is different. A lot of things may be different, such as memory size, mmio addresses, keys, key 'locations' (memory) and so on. The camera likely won't boot anymore but you're free to try if you can spare one. Also, since the firmware is stuffed with assertions, even if it does boot I doubt it'll run properly.
Some differences which are likely show-stoppers:
- Different cropfactor and sensor sensitivity -> different sensor
- Dual DIGIC III vs single DIGIC III
- Different AF units
- No support for EF-S lenses