[dchest]

Start from the left column (Learning Go): http://golang.org/doc/docs.html and continue to the bottom.

Watch "Practical Go Programming": http://osdc.blip.tv/file/4432146/

Watch "Writing Go Packages": http://www.youtube.com/gocoding#p/u/0/jDWBJOXs_iI

Read language specification.

Edit: If you prefer books, here's a CC-licensed, still in development, book by Miek Gieben "Learning Go": http://www.miek.nl/files/go/ (grab the latest PDF; alternatively, here's Git repo: http://miek.nl/cgi-bin/gitweb.cgi?p=gobook.git;a=summary)