Please keep in mind this post is from 2013 and may no longer be valid.
So for some reason you have multiple machines to manage but don't have SSH-keys on them. It's still possible to use parallel-ssh and sudo without having to enter any passwords. Create a file with your password in it (suggest you remove the file as soon as you are done). Then install parallel-ssh and sshpass :
apt-get install sshpass pssh
Use the programs like this:
sshpass -f ~/tmppass parallel-ssh -I -A -h hostsfile "sudo -S yum upgrade -y" < ~/tmppass
tmppass is your password file. For parallel-ssh, -I reads from input and -A asks for password. And for sudo, -S reads the password from stdin.
You might also want to disable StrictHostKeyChecking:
sshpass -f ~/tmppass parallel-ssh -x "StrictHostKeyChecking=no" -I -A -h hostsfile "sudo -S yum upgrade -y" < ~/tmppass