The MechWarrior Online Forums have patch notes for a new open beta 5 that's now live in the MMO mech game. Here's word on how this adds ECM, a new mech, and eight-player matchmaking:

ECM is here and personally I can’t wait to ruin some streak cats day with this excellent piece of equipment. I am going to be honest with you ECM is a game changer so let us know how you feel about ECM on the forums because lately I think you guys have been holding back and not telling us how you really feel.

The Cataphract Hero Mech “Ilya Muromets” is in this patch with an excellent skin by our man Hayden. What can I say about this Mech? “Ilya?.. More Like Kill ya!” is how our tools programmer Kyle L put it and I have to agree.

I can’t remember but I think you guys wanted 8-player groups too right? Well those are in there too. You choose “8-Player Required” when creating a group. You will require 8-players to launch and your groups will only be matched against other 8-player groups.