Currently, pkg/crypto/x509/root_unix.go lists a handful of root certificate locations. It probably needs to grow an entry for solaris-ish systems.
The current list is:
"/etc/ssl/certs/ca-certificates.crt", // Debian/Ubuntu/Gentoo etc. "/etc/pki/tls/certs/ca-bundle.crt", // Fedora/RHEL "/etc/ssl/ca-bundle.pem", // OpenSUSE "/etc/ssl/cert.pem", // OpenBSD "/usr/local/share/certs/ca-root-nss.crt", // FreeBSD/DragonFly
None of which exist on at least openindiana and smartos (in fairness, I can't find a suitable file which does exist, though). This means 'go get' won't work.
(unless I've missed something, since I was doing this based on the main go source tree, and may have missed any port-specific documentation that's only in this tree...)