debian-archive-keyring is already the newest version.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
OK
Get:1 http://security.debian.org squeeze/updates Release.gpg [836 B]
Ign http://security.debian.org/ squeeze/updates/main Translation-en
Ign http://security.debian.org/ squeeze/updates/main Translation-en_US
Get:2 http://debian.saltstack.com squeeze-saltstack Release.gpg [836 B]
Ign http://debian.saltstack.com/debian/ squeeze-saltstack/main Translation-en
Ign http://debian.saltstack.com/debian/ squeeze-saltstack/main Translation-en_US
Get:3 http://ftp.us.debian.org squeeze Release.gpg [1,672 B]
Ign http://ftp.us.debian.org/debian/ squeeze/main Translation-en
Ign http://ftp.us.debian.org/debian/ squeeze/main Translation-en_US
Get:4 http://security.debian.org squeeze/updates Release [86.9 kB]
Get:5 http://debian.saltstack.com squeeze-saltstack Release [3,750 B]
Get:6 http://ftp.us.debian.org squeeze Release [96.0 kB]
Ign http://debian.saltstack.com squeeze-saltstack/main amd64 Packages
Get:7 http://backports.debian.org squeeze-backports Release.gpg [836 B]
Get:8 http://backports.debian.org/debian-backports/ squeeze-backports/main Translation-en [247 kB]
Ign http://debian.saltstack.com squeeze-saltstack/main amd64 Packages
Get:9 http://debian.saltstack.com squeeze-saltstack/main amd64 Packages [3,419 B]
Get:10 http://security.debian.org squeeze/updates/main amd64 Packages [363 kB]
Get:11 http://ftp.us.debian.org squeeze/main amd64 Packages [6,538 kB]
Ign http://backports.debian.org/debian-backports/ squeeze-backports/main Translation-en_US
Get:12 http://backports.debian.org squeeze-backports Release [109 kB]
Ign http://backports.debian.org squeeze-backports Release
Get:13 http://backports.debian.org squeeze-backports/main amd64 Packages [386 kB]
Fetched 7,837 kB in 5s (1,505 kB/s)
Reading package lists...
W: GPG error: http://backports.debian.org squeeze-backports Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 8B48AD6246925553
Reading package lists...
Building dependency tree...
Reading state information...
The following extra packages will be installed:
  libpgm-5.1-0 libzmq3
The following NEW packages will be installed:
  libpgm-5.1-0 libzmq3 python-zmq
0 upgraded, 3 newly installed, 0 to remove and 73 not upgraded.
Need to get 787 kB of archives.
After this operation, 1,992 kB of additional disk space will be used.
WARNING: The following packages cannot be authenticated!
  libpgm-5.1-0
E: There are problems and -y was used without --force-yes
 * ERROR: Failed to run install_debian_6_deps()!!!
[ERROR   ] Failed to deploy 'example.com'. Error: Executing the command '/tmp/.saltcloud/deploy.sh -c /tmp/.saltcloud' failed
Traceback (most recent call last):
  File "/usr/lib/pymodules/python2.7/salt/cloud/__init__.py", line 1620, in run_map
    profile, local_master=master_name is None
  File "/usr/lib/pymodules/python2.7/salt/cloud/__init__.py", line 854, in create
    output = self.clouds[func](vm_)
  File "/usr/lib/pymodules/python2.7/salt/cloud/clouds/digital_ocean.py", line 435, in create
    deployed = salt.utils.cloud.deploy_script(**deploy_kwargs)
  File "/usr/lib/pymodules/python2.7/salt/utils/cloud.py", line 753, in deploy_script
    deploy_command
SaltCloudSystemExit: Executing the command '/tmp/.saltcloud/deploy.sh -c /tmp/.saltcloud' failed
[INFO    ] Complete
example.com:
    ----------
    Error:
        Executing the command '/tmp/.saltcloud/deploy.sh -c /tmp/.saltcloud' failed