Deployable Sensor Array	The Sensor Array is equiped with a state of the art radar. When they are deployed they can scan a certain area for any disturbances which would be subterranean vehicles sneaking into the base. Early detection helps prevent some nasty effect later on.
Dropship	The Dropship is a very, very large "unit" that can be ordered only before a mission. During the mission, it will come down and drop off the specified units. You can't control the dropship, other than the units that are contained within, and possibly the drop-off point.
Weed Eater	Nod answer to the Tiberium problem is far more devilish that GDI's. Their Tiberium Eater acts to same as GDI's, only it collects juices from the mineral, and can take it back to a Missile Silo. When enough juice is collected, you can build a Bio-Missile, which you can launch at the enemy base, starting new Tiberium growth.
Repair bot	This useful little Nod unit will have the ability to repair vehicles right in the heat of battle.
Mobile Construction Vehicle	The MCV is one of the most important vehicles in the game. You can drive it around until you reach a sensible spot, where you deploy it. It then becomes the Construction Yard, the structure that allows you to build other structures.
Harvester	The Harvester will go out into the Tiberium fields and use it's "claws" to collect Tiberium for processing. Another very important vehicle, as it provides you with a steady income. This unit is so important, that it will now be possible to have a Harvester truce in multiplayer, making it impossible to attack the Harvesters.
Hunter Seeker Droid	Building these guys can be very useful. They will automatically search out an enemy unit and attach to it, allowing you to see what it sees. Once you get bored of that, you can blow it up, damaging or killing the unit. It's only detectable by sight by the player. Drawbacks are that you can only have one at a time and you can't control what it attaches to.