78. can a creature benefit from multiple commander's strikes by multiple warlords in the same round?
Yes. One free action per Turn is not the same as one per round. If you had a party of 1 rogue and 4 warlords, yes, each one could use commander's strike or Direct the strike, and the rogue would get an attack for each one. Each warlord has his/her own turn.
And with the revised striker rules from essentials, the rogue would get to add sneak attack damage with every attack, provided he/she had combat advantage (say, from a flank-buddy warlord).