PS3fanboy has posted a in detail look at the multiplayer classes of Killzone 2 which look to bring some tactical teamwork into the Killzone 2 arena. If you choose ISA or helghast the effects of the classes will be the same.

Rifleman:

The default multiplayer character is assigned when no primary badge is selected. A secondary badge may still be added. Riflemen can start with most weapons, except for the specialized ones.

Engineer:

Primary badge ability: Sets up an automated turret which targets the enemy.

Secondary badge ability: Repairs ammunition dispensers, mounted guns, and automated turrets.

Medic:

Primary badge ability: Revives downed team mates.

Secondary badge ability: Throws a health pack, which can be picked up by other players.

Scout:

Primary badge ability: Uses a cloaking suit to become near-invisible.

Secondary badge ability: Tags all on-screen enemy players with a hidden marker, which broadcasts their coordinates to team mates.

Assault:

Primary badge ability: Dons heavy armour twice as strong as normal.

Secondary badge ability: Temporarily boosts running speed.

Tactician:

Primary badge ability: Throws a coloured smoke grenade, which serves as a spawn point.

Secondary badge ability: Requests air support from a sentry bot which targets the enemy.

Saboteur:

Primary badge ability: Assumes the disguise of a randomly selected enemy player.

Secondary badge ability: Throws a sticky, proximity-activated C-4 charge.

These classes can bring some great teamwork to Killzone 2, so if you are in a clan this could get you excited.