Using GnuTLS avoids the licensing issues that can arise from employing the more common OpenSSL package. For this reason, certain packages such as OpenLDAP are compiled with support for GnuTLS instead of OpenSSL in recent releases of Ubuntu.
In fact, on one of my Ubuntu 13.10 systems I ran ldd on
It's not hard to admit errors that are [only] cosmetically wrong. -- J.K. Galbraith