What the Voltage Tweak HD 4890 from ASUS does is let us expand upon our overclocking abilities. For years the only way you could adjust the voltage on the card was by soldering little bits and pieces to your card, which not only is hard for most people but also voids the warranty.
We're not sure if this ability is going to be something we see more and more often in cards, but it would be nice. Even if the companies don't offer us a huge range, just something safe that gives us the ability to gain even more MHz if we feel the need to.
As for the rest of the card, there isn't anything too out of the ordinary. We've got the usual spin, plenty of extra software along with a CD wallet. We've also got all the standard cables that we need to get the card up and running.
All in all the HD 4890 Voltage Tweak from ASUS is a nice version of the HD 4890 which lets us experience something new. Hopefully we do see more of this technology come into play with other models in the future.