Most of this by now is old hat but just to post more info.

- Built-in flash memory
- Download games to flash drive via Nintendo DSi Shop
- First games announced are redesigned versions of the two Brain Age games
- No cartridges necessary, games will be accessible through DSi menu
- Two cameras: one facing forward and another facing back at user
- Real-time imaging software included (Combine pics, distort faces, grafitti)
- Music Player: AAC format, drag and drop from Computer to SD card
- Adjust pitch and speed of AAC files, audio filter (listen only to instruments or vocals)
- Record voice via microphone and alter it
- All software will be pre-loaded with DSi
- Smaller design, no GBA slot
- Coming to America “well into” 2009 due to high demand of DS still present

Source