Since Look developed the first clipless pedal for Bernard Hinault and Greg Lemond back in 83 they have never stopped innovating the the connection of man to the drivetrain of the bicycle.
In 2005 Look unveiled the biggest design advancement in clipless pedals, the KEO, pronounced kay-o.  At first glance there are some real similarities to the delta design that revolutionised cycling.  There are still 3 holes, the cleat is delta shaped and engagement is the same.
This about where it all ends.  Whilst the cleat is delta shaped and connects to the shoe via the same mounting points.  Whilst the new Keo cleat is actually smaller it supports a larger contact area to the pedal of 259mm vs 213mm of the older delta cleat.
Interestingly the contact areas of the 4 major brands are as follows:

Look Keo 259mm of contact
Speedplay 188mm of contact
Shimano Dura Ace 186mm of contact
Time 126mm of contact

Look Pro riders have commented the larger contact area avoids the feeling you are "standing on an acorn".

Developed in conjunction with the leading Pros of this generation Petacchi, McEwen, Valverde etc the power transfer measurement from cleat to axle has been reduced by a further 6mm to deliver the power more directly.
A grey cleat has been introduced which offers 4.5 degrees of float as asked by leading sprinters Cipollini and Petacchi, currently using the grey it is easy to understand why this has become so popular, whilst offering free float the connection still feels secure.  For riders wanting a fixed connection there is the black version and for those wanting the full 9 degrees the standard red is still the most popular.

For 2006 the Keo technology has now been used throughout the range giving riders of all abilities and specialties the benefits of the Keo. 

Keo Carbon Ti
Keo Carbon
Keo Sprint carbon composite
Keo Classic carbon composite

Having now put both the Cabon Ti's and the Classics through their paces, the mechanics are the same, the cleat sits in the same position 6mm closer to the axle on both but the major benefits for the Higher specced Carbons are the overall lighter weight (rotational) and the increased release retention ability for those riders competing at high levels.