Go lang released 10-13
groups.google.com
groups.google.com
Until then, it's awfully hard to get behind - if the development is going to follow Google's Java open source process (release a shiny gem every 4 months, zero community involvement), it's hard to justify making any investment in it. Guava's just a toolkit and is useful by itself, Go needs an ecosystem.
A lot of 3rd party packages are also listed at http://go-lang.cat-v.org/.
The goinstall command (http://golang.org/cmd/goinstall/) can automatically install packages from Google code hosting, GitHub, BitBucket and Launchpad.
The Go development process is very open, and a lot of contributions have been accepted from non-core developers.