The closed beta of Halo 4's multiplayer is on-going, and is expected to lead up to the game's release on November 6. Despite the fact that its participants have signed a non-disclosure agreement, the beta hasn't been the most secure, and leaks of its content have been surfacing for some time now.
The latest of the leaks has surfaced on NeoGAF from a poster named juryben, who used the screenshots as an attempt to bring traffic to his own website. He has since been banned from NeoGAF for skirting the site's rules about leaks. As these images are now public, there's no reason why we can't show them to you.
The screenshots appear to contain Halo 4's railgun weapon, which has only been hinted at thus far. Also present in the images is a Warthog, which gives us a small glimpse of the game's vehicular combat.
Don't mind the redacted out text—the poster added those redactions to protect the identities of the other players in that play session.