http://www.eagb.net/advance/hr42.html
The reason i post this here is because I think this would be wonderful for the DS (given it's higher resolution and it's more normal aspect ratio).
As is though, i'm really interest in it.
Using the SP/DS you'd get a colourfull bright screen to watch video feed off any device, and you should have hours of video (on one charge) in your pocket.
Since it doesn't need to pluged into a power source (like a standard monitor) it's one less wire to work with when on site.