Yep. I don't think they are really copyrighted, there rather appears to be special laws about them (as above). And the problem I forgot to mention: if we include them in Wikipedia it means we are putting them under a new licence, the GFDL, which knows nothing about these restrictions (which still apply). Or do I misunderstand the concept of GFDL here? So it seems we have a conflict here.

The GFDL only licenses the rights under copyright. The restrictions you mention above are more akin to _trademark_ restrictions, about which GFDL has nothing to say (nor should it). Just because it's OK to put a picture of a Coke can here--or even put such a picture in the public domain--that doesn't mean you could download it and print it on your own cans and sell them as Coke. They still have the right to the use of their logos and such for identification.