Henchie was asking me about Warfare tonight and I realised that theres quite a few people that have UT3 and possibly don't play it because they haven't a clue whats going on, most of the UT3 players that play Warfare came from playing UT2004 Onslaught which was the original Warfare as such so i forget sometimes that its so new to some people so guess what....I am going to attempt to do a tutorial, I know it scares me also but here goes nuthin...
First of all go to settings, click on HUD and untick
Zoomed Minimap The Minimap should look like this

This is important because this is how you work out whats going on, the correct direction you are going etc...
The aim of Warfare is to destroy the other teams Powercore, to do this you must capture a chain of linked nodes from your Core to the enemys Core, most maps have a fairly linear layout in relation to Nodes but some maps have multiple routes to the Core providing cut off nodes etc... this is when it gets more tactical in relation to what Node to go for when Respawning
NODE 
Nodes can be destroyed by any weapon as long as it is un-shielded, as in one of your controlled nodes links to it, you build a Node fast with link Secondary or it builds itself after a period of time, to capture an unlinked Node you just run over it
Warfare is basically join the dots, each team starts off at their base, each team has a Powercore, the aim is to destroy the other teams Powercore
POWERCORE
The Minimap example above is from a map called Downtown, you might have noticed the unlinked Node, many maps have these Spur Nodes, these can provide a number of uses
They can be on a timer, as in hold the node for 60 seconds and the enemy Core gets depleted from 100 to 80 even if its shielded
They can provide crucial vehicles, on Downtown it spawns a Tank which is pretty powerful on this map because there are no flyers, only ground vehicles
They have other uses, really its map specific, so no point at this stage in going through it
THE ORB
The Orb can be taken to any node and when you walk over the Node it kills the Node completely if its controlled by the enemy and builds it completely, it can change the course of any game as it captures a linked Node completely in seconds
You can also use the Orb to shield a node by standing close to it whilst holding the Orb, again a major tactic that can swing a game
Here's an overhead of the map WAR-OnyxCoast
Heres is a map overhead from WAR-OnyxCoast, you can get all the stock map overheads from here
http://http://www.beyondunreal.com/articles/warfare-key-guides/
Anyhow please feel free to ask questions because once i got into this I realized its really just the tip of the iceberg in relation to Warfare, once you get it down though it increases your fun level majorly, also if any Warfare peeps want to add stuff please do, try it with images like i did, they speak a thousand words and are pretty to look at
I haven't even started with the Weapons, Hoverboard, Vehicles etc... so plz feel free