You can think at the new DSi like this: DS + (photo)camera + iPod. It does everything that the old DS did but better (the screens are bigger – 3.25″), it has a dual-video camera (inside/outside 640×480 resolution) and you can listen to music now, thanks to the flash memory and the new SD card slot.
The estimated price is $180 but, unfortunately, a release date for USA or UE is not available.