While little is known about the GTX 760 currently, it appears that someone from PC Games Hardware has mistakenly taken a picture of the packaging of the GTX 760 card and published it. The reason we say that it was accidental is because it was included in a roundup of three GTX 780 cards, and it seems that someone may have accidentally swapped the MSI GTX 780 packaging for that of MSI's GTX 760. From the packaging, we can see that the card will carry the TwinFrozr cooler, and will be themed as part of the Gaming series of PC components, meaning that it will be black and red. The box also indicates that the card will be factory overclocked.
An earlier report did shed some light onto the GTX 760's specifications, though their likeliness remains questionable. According to these specifications, the GTX 760 would not be very different from the GTX 660 Ti, featuring higher clock speeds and a wide memory interface. More details here.
Reports indicate that the GTX 760 is expected to launch this week still with an MSRP of $299.