The folks over at Pirahna games have released the first developer diary for MechWarrior Online which covers the four main design pillars for the game:
Mech combat - Giant robots fighting each other and blowing each other up
Information warfare - Combat is now line of sight/Lance dependent so no more targeting and shooting over terrain without help from a team member
Role Warfare - every mech is important and it's not just an arms race to get a 100 ton Atlus mech, smaller mechs play a key role in the game (see #2 above)
Community Warfare - allowing people to play against each other and share it socially
There's not a lot of new footage here but it does show off how gorgeous the game is. Here's the full thing so you can get more detail on this awesome looking game.