The first photos taken from location work on the second series of Doctor Who have made their way to the Internet: what appears to be a Czech photo archive of David Tennant pictures from the Splash News photo service, including pictures of Tennant and Piper rehearsing and some eerily decorated Santas that appear to be aliens or zombies beneath. The photos can be found by clicking here; the first 13 in the set are the ones from this filming, with other shots of Tennant in other locales. (Don't bother registering for larger photos; you won't be able to gain entry.)
UPDATE: A second collection of images from official press photographers is online, from the World Entertainment News Network; you can click here to view them. These also include Camille Coduri and Noel Clarke as well as David Tennant and Billie Piper.
(Thanks to John Starkey, and the folks at david-tennant.com)