OLED screens for small devices are going to be in very short supply soon if iPhone rumors are to be believed
But I imagine they'll be really high resolution.
Samsung use oleds in their low end phones and they're 720p. I'm sure if Nintendo were that way inclined they'd have been able to get a contract with a supplier.
Still it's done now, and I guess I should be lucky that it's not a TN panel, I just hope we don't have a lottery like the 3ds with some having IPS and some having TN. That would be annoying....