I wrote:
(I was testing with gnuPG 1.0.4 also, and it seems to do the right thing.)
actually it looks like gnuPG does the same thing as PGP.
I'm presuming the keyID includes the private key components for private
keys, so the private key has a different keyID even though the gui doesn't
display it that way, if you display the contents of the private key file.
So I guess you have to compute the keyID rather than reading it in form the
secret key file if you're working from a secret key and not a public key.
Adam