Earlier this week Gamestop sent a memo to its retail locations revealing that the Onyx/Black Nintendo DS Lite system has been discontinued. Once stock is gone, as the memo informs, retailers are to remove the display boxes from shelves.
In its daily newsletter, Gamestop writes that "DS Lite Onyx hardware systems have been discontinued and stores will no longer be replenished on this product. Once your store sells through its current stock of this item, please remove any empty DS Onyx display boxes (onyx color only) from the sales floor and discard."
Though no other information was revealed by Gamestop, it's very possible that Nintendo has discontinued the Onyx DS Lite color in anticipation of the upcoming DSi launch in the US, which is rumored to happen this April. The Onyx DS Lite and the Japanese Onyx DSi systems look strikingly similar, so removing the Onyx DS Lite from active inventory may be a strategy by Nintendo to eliminate retail confusion for when the company releases the DSi this year.
Nintendo of America has a history of only releasing a single color system in a new system launch, so this may be indication that Onyx will be the official launch color in the US.
Calls into Nintendo of America have been made, but currently the company has no comment.