This is a long awaited competition for robotics is here. This should hopefully drive research in this field. Many humanoids have always been showed in staged environments given the difficulties in getting them to perform in the real world.
There are many difficulties that has to be overcomed but actuator design. Dr. Gill Pratt, DARPA’s program director, is in-charge of this challenge. He is familiar with this field, given he is the inventor of the Series Elastic Actuator at MIT where he was developing robots for locomotion. He’s the right person to drive this development.
Here’s a good article about actuators used in legged robots.
Robocup has a similar goal in development of humanoids as well.
By mid-21st century, a team of fully autonomous humanoid robot soccer players shall win the soccer game, comply with the official rule of the FIFA, against the winner of the most recent World Cup.