IF there are 100 or fewer repos, simply run:
curl -u $YOURUSERNAME -s https://api.github.com/orgs/$ORGNAME/repos?per_page=100 | ruby -rubygems -e 'require "json"; JSON.load(STDIN.read).each { |repo| %x[git clone #{repo["ssh_url"]} ]}'
(per https://gist.github.com/caniszczyk/3856584 )
and wait.
(Note when prompted for password, they do not mean your github web password, they mean your oauth token - all command line requests for password are actually for oath token. See https://github.com/blog/1509-personal-api-tokens to generate a token.)