Yes my first post was a guess about how Namecoin works.
After reading up around here:
what I said is wrong (yeah highlighted that myself
(well most likely wrong since I still haven't read the code and no one seems to know how it really does work)
However, as stated before (correctly) cgminer cannot mine 2 chains at the same time.
That is not what it would appear namecoin is doing.
The description above by DeathAndTaxes is completely clueless (you missed completely what "create hash" is)
This is of course a guess - but it would appear that namecoin is putting extra information in the coinbase - i.e. increasing the bitcoin block size.
(I'm guessing this due to a discussion with luke-jr)
As I already said, I'll be reading the code to determine how it works if no one can actually describe it.
It would appear that is my only option coz on one reading here does know how it works and thus is able to describe it properly.
Edit: Well I guess I now have the link to get the official code at least ... from DavinciJ15 :
http://dot-bit.org/Merged_Mining(can't remember where I got it last time I compiled and ran it)