Squashed commit of the following, plus some streamlining (MPD).

commit e00368e7c65c65bed11fcaaf83fe8b093dbf492e
Merge: 2ea7110 c039aa0
Author: Michael DeHaan <michael.dehaan@gmail.com>
Date:   Thu May 10 01:43:10 2012 -0400

    Merge branch 'devel' of https://github.com/weaselkeeper/ansible into weaselkeeper-devel

commit c039aa0915
Author: Jim Richardson <weaselkeeper@gmail.com>
Date:   Fri May 11 17:55:13 2012 -0700

    cleanup and simplification of ANSIBLE_REMOTE_TMP feature

commit d87f15b796
Merge: 5917aba 4c2fd25
Author: Jim Richardson <weaselkeeper@gmail.com>
Date:   Fri May 11 17:30:16 2012 -0700

    Merge branch 'devel' of github.com:weaselkeeper/ansible into devel

commit 5917aba761
Author: Jim Richardson <jrichardson@classmates.com>
Date:   Wed May 9 11:25:45 2012 -0700

     ANSIBLE_REMOTE_TMP environment variable sets where ansible will stuf tmp files on remote host.  Default is /var/tmp for root, and $HOME/.ansible/tmp for non-root

commit 4c2fd25777
Author: Jim Richardson <jrichardson@classmates.com>
Date:   Wed May 9 11:25:45 2012 -0700

     ANSIBLE_REMOTE_TMP environment variable sets where ansible will stuf tmp files on remote host.  Default is /var/tmp for root, and $HOME/.ansible/tmp for non-root

lib/ansible/constants.py

@@ -23,6 +23,8 @@ DEFAULT_HOST_LIST      = os.environ.get('ANSIBLE_HOSTS',
     '/etc/ansible/hosts')
 DEFAULT_MODULE_PATH    = os.environ.get('ANSIBLE_LIBRARY',
     '/usr/share/ansible')
+DEFAULT_REMOTE_TMP     = os.environ.get('ANSIBLE_REMOTE_TMP', 
+    '/$HOME/.ansible/tmp')
 
 DEFAULT_MODULE_NAME    = 'command'
 DEFAULT_PATTERN        = '*'

lib/ansible/runner.py

@@ -247,13 +247,13 @@ class Runner(object):
                 if self.remote_user == 'root':
                     args = "%s metadata=/etc/ansible/setup" % args
                 else:
-                    args = "%s metadata=$HOME/.ansible/setup" % args
+                    args = "%s metadata=%s/.ansible/setup" % (args, C.DEFAULT_REMOTE_TMP)
         else:
             if not 'metadata' in args:
                 if self.remote_user == 'root':
                     args['metadata'] = '/etc/ansible/setup'
                 else:
-                    args['metadata'] = "$HOME/.ansible/setup"
+                    args['metadata'] = "%s/.ansible/setup" % C.DEFAULT_REMOTE_TMP
         return args   
  
     # *****************************************************
@@ -667,13 +667,9 @@ class Runner(object):
     def _get_tmp_path(self, conn):
         ''' gets a temporary path on a remote box '''
 
-        # The problem with this is that it's executed on the
-        # overlord, not on the target so we can't use tempdir and os.path
-        # Only support the *nix world for now by using the $HOME env var
-
-        basetmp = "/var/tmp"
-        if self.remote_user != 'root':
-            basetmp = "$HOME/.ansible/tmp"
+        basetmp = C.DEFAULT_REMOTE_TMP
+        if self.remote_user == 'root':
+            basetmp ="/var/tmp"
         cmd = "mktemp -d %s/ansible.XXXXXX" % basetmp
         if self.remote_user != 'root':
             cmd = "mkdir -p %s && %s" % (basetmp, cmd)