[go-nuts] Can't shake "not a package file" error

I get this type of error for any non-standard lib package I try to use.
  I'm running go1.1.2 but have also tried 1.2rc1 with a similar but
different error.
./server.go:7: import
/Users/jayson/workspace/Go/pkg/darwin_amd64/github.com/gorilla/mux.a: not a
package file

Here's the code:

package main

import (
   "rexbro"
   "fmt"
   "net/http"
   "github.com/gorilla/mux"
   // "os"
   "encoding/json"
)

// var router = new(mux.Router)
const port = ":3000"

func main() {
   r := mux.NewRouter()
   r.HandleFunc("/", HomeHandler)
   r.HandleFunc("/free_agents", FreeAgentHandler)
   http.Handle("/", r)
   http.ListenAndServe(port, nil)
}


HELP!