The standard Go distribution includes a Go syntax file for Vim in go/misc/vim/.
Place $GOROOT/misc/vim/syntax/go.vim in ~/.vim/syntax/ and put the following in ~/.vim/ftdetect/go.vim:
au BufRead,BufNewFile *.go set filetype=go
An alternative indent file for Vim by Alecs King can be found here.
The gocode daemon by nsf includes a vim script to do autocompletion.
See the vim-golang repo in Github for alternative syntax highlight, auto-indentation, gofmt and other useful scripts and plugins.
