It appears time.Now().UTC().Unix() still returns a local timestamp. If this doesn't work, I'm not sure how to get a UTC timestamp.

timestamp.go

package main

import "fmt"
import "time"  

func main() {
	local, _ := time.Now().Zone()
	fmt.Println("Local timezone:", local)
	fmt.Println("UNIX local timestamp:", time.Now().Unix())
	fmt.Println("UNIX UTC timestamp:", time.Now().UTC().Unix())
}

timestamp_darwin.txt

$ go version
go version devel +d4c3e6c8b141 Wed Apr 24 10:40:29 2013 -0700 darwin/amd64
$ go run timestamp.go
Local timezone: MDT
UNIX local timestamp: 1366842519
UNIX UTC timestamp: 1366842519

timestamp_linux.txt

$ go version
go version devel +ce5b441d2fc6 Sun Apr 14 09:22:57 2013 +1000 linux/amd64
$ go run timestamp.go 
Local timezone: MDT
UNIX local timestamp: 1366843096
UNIX UTC timestamp: 1366843096