We can't be exactly sure what the Taunka's role will be. The last paragraph in the update says that we'll soon recognize their "colossal hearts and unshakeable resolve." To me, this sounds like a possible faction we'll be grinding rep for. Perhaps something like the Orgri'la faction, where at first the Orges are hostile, and then they are friendly.
An interesting comment on WoWWiki suggest that Chieftain Ashtotem, known from a screenshot of the Howling Fjord in Northrend, might be a Taunka. What do you think? Personally, I think it's possible. The yellow name also lends credence to the theory that this might be a reputation faction.
We'll keep you updated on all the future Wrath of the Lich King news.