I was just about to say that white is probably the first of many colours.
All the way back to the original Game Boy, Nintendo handhelds have come in multiple colours. The DS already has red and blue and other special editions. This new DS is looking like part of the new Nintendo family with its similar style as the Revolution, and it's even expected that the Revolution will come in multiple colours.
So for those of you who don't like the white, expect black (iPods come in black too, if Apple's style is what they're emulating) and probably platinum, and a slew of other colours before long. Special editions, too. A Super NES Limited Edition? (I suppose that'd be more likely if they ported over more Super NES games, though, which seems unlikely once the Revolution's download service launches - unless they had DS features, oooh!) These would probably be easier to make custom skins for, as well.