The appliances in question, which "reads" film negatives and reproduces the photos on a computer, have been found to contain the Conficker.B variant.
According to H-Online, the virus is contained in the DCIM.exe and autorun.inf files, but since Microsoft has disabled the AutoRun function on writeable media, the only way for users to get infected is to run the executable themselves.
Both Hama and Tchibo have confirmed the incident and the retailer advised users to remove the malware via paid and free AV products, or to alternatively bring the device in for a refund.
It has not been explained how the devices came to be infected in the first place, but my bet is that it happened inadvertently during manufacturing when they came in contact with an infected computer involved in the production process.
This is not the first time that new and unused electrical devices were found to contain malware. In March 2010, a Energizer DUO USB recharger was discovered being sold bundled up with a backdoor Trojan, and a day later a HTC Magic smartphone sold by Vodafone has been spotted containing the Mariposa bot client.