Dear Fabian,
I know it's quite late for changes and I am sorry for not coming up with the following issue earlier.
The CentOS logo makes use of a commercial font called Denmark.
Hmm, no, the name seems to be HandelGotDBol, but that's a detail though :-)
At least not since Alain or I do the artwork. We've used Denmark from the start:
http://wiki.centos.org/ArtWork/Fonts