No Photoshop, no fancy light tricks, and certainly no time travel were used here. Instead, this 100-year-old Russian photo was taken using the Harris Shutter Effect, which causes those bright, saturated colours that look more in keeping with today's photography.
First, a little bit of context for this photo. The three peasant girls were shot by the Russian photographer Sergey Prokudin-Gorsky in 1909, who was renowned for taking the only known colour photo of Leo Tolstoy, in 1908. He caught the eye of Tsar Nicholas II, who hired him to document Russian life in colour - specifically, using the Harris Shutter Effect.
Invented by Kodak, the bright colours are caused by re-exposing a frame in red, green and blue filters. Anyone who's tinkered with lomography cameras - or any film camera which allows for multiple exposures - should be familiar with the idea, where the same subject is shot several times, only changing the colour filter each time. The result, as you can see in the photo above and the countless others available on the Library of Congress' site, is something that appears so bright and modern it's as if today's technology existed back then. Or at the very least, that the photography subject has a valuable collection of costumes on hand. [Library of Congress via Big Picture via Laughing Squid via Photojojo]
UPDATE: Some people have asked for more information on Prokudin-Gorsky's technique. The photo below, taken from Wikipedia, shows how he took three individual monochrome photos with an exposure of around three seconds a shot, and with different-coloured filters (red, blue and green), he made them into one photo by projecting all three slides together. True, they've been constructed into one digital photo in the 21st century by digitally layering them, but they look no more different now than they would've appeared in Prokudin-Gorsky's day, when people would huddle around a projector watching the magic flicker on-screen.