If you want to contribute (implement something from the current list, or
anything), contact the developer's mailing list (gnutls-dev@lists.gnupg.org),
in order to avoid having people working on the same thing. 

Current list:
* Check opera (which sends an closure alert during the handshake
  which we do not read).
* Make the current ciphering code a bit more abstract to
  allow easy integration with TLS hardware.
* Allow adding multiple subject alternative names.
* Allow verifying of certificates on their reception.
* Verify added CRLs
* Document the format for the supported DN attributes.
* Add support for Certificate Extensions Profile for Qualified 
  Certificates (rfc3039)
* Audit the code
* Add gnutls_certificate_set_openpgp_keyring()
  function, similar to gnutls_certificate_set_openpgp_key().
* Use subkeys with the 0x20 flag in openpgp keys (if present),
  instead of the main key.
* Add function to extract the signers of an openpgp key. Should
  be similar to gnutls_x509_crt_get_dn_oid().
* Add function to verify an openpgp key against a plain key.
- Convert documentation to texinfo format
- Allow sending V2 Hello messages. It seems that some (old) broken 
  implementations require that.
- Add Kerberos support

(+) Means high priority 
(*) Means medium priority
(-) Means low priority (ie. nobody is interested to develop that)