Just noticed a Sprint image of the back of the NS4G that makes it seem like it will have a more 'textured' back surface, much like the white version of the NS.
5th image over, taken from the mobile version of Sprint's Nexus S page:
The back didn't look like that in the early hands-on videos...
Here's hoping, would be a nice touch!
Engadget's mini review of the white NS mentioned the textured back around 6:15:
White Nexus S with AT&T 3G bands hands-on! (video) -- Engadget
5th image over, taken from the mobile version of Sprint's Nexus S page:

The back didn't look like that in the early hands-on videos...
Here's hoping, would be a nice touch!
Engadget's mini review of the white NS mentioned the textured back around 6:15:
White Nexus S with AT&T 3G bands hands-on! (video) -- Engadget