I agree. Although it is not my decision, I think the "polite" thing to do
would be to leave the CentOS trademarks out, but give adequate and glowing credit to the CentOS developers that made the OS possible. Just like the CentOS developers do to upstream whenever they can.
I think that depends on the project, for mythtv I expect this would mostly be a matter of building many packages for a (mostly) unmodified base centos system. As such you could probably have most of these in a base 'centimyth' repo, and pull the rest directly from the centos repos. I think some sort of logo being a merger of the centos logo and mythtv logos would be most appropriate here. Of course this would require approval from the dev team. In Axel's or Dag's case I expect such approval would be for the most part a formality (but would still need to be given!)... For other projects... who knows ;-)
[can you see the trust I have for atrpms, dag and rpmforge? Thanks for the awesome work guys]
Now going back to getting CentOS5 working on a santa rosa macbook pro (out of the box even the network card doesn't work).
Cheers, Maciej