Threefish cipher in GnuPG?

[Robert J. Hansen]

> Anyway, just out of curiosity, are there plans on including Threefish in
> GnuPG? Or reasons why it hasn't been nor will be?

RFC4880 has identifiers for the following symmetric ciphers:
Unencrypted, IDEA, 3DES, CAST5-128, Blowfish-128, AES in three key
sizes, and Twofish-256.  Supplemental RFCs (5581) have added identifiers
for Camellia in three key sizes.

If you can get the IETF to release an RFC for Threefish in OpenPGP, it's
very likely GnuPG will include Threefish support.  But without that,
it's very unlikely.