Observer Mode

Ever wish you could see championship battles firsthand and catch Guild Wars legends in the making? Want to check out a PvP map before you try it? Are you looking to scope out the competition and pick up new strategies? Maybe you just want to watch your friends battle to victory and see your enemies battered without putting in the effort yourself? If the answer to any of those questions is “yes,” Observer mode is made for you. You can choose to enter Observer mode from the main menu (or by pressing B) to check out a guild battle or a guild tournament battle going on in one of the PvP arenas. To leave Observer mode, use the menu, hit B again, or hit M to use ordinary map travel (which will take you back to the character you are playing).

Using Observer Mode:

You can only use Observer mode in towns and outposts.
Press U while in Observer mode to open or close the map overlay (1 on the screenshot).
Matches are made available for observation 15 minutes after the match starts. If you are the first one to view the match it will play back from the beginning.
Any observer who joins after the first person will enter Observer mode as the match is in progress. Later observers may miss the beginning of the match, but will be able to view it simultaneously alongside all other observers present.
The overhead view centers on a random player when you enter Observer mode. You can switch your focus to another character by left-clicking on that character.
You can also change your view by left-clicking on a character’s icon on the observation map (1 on the screenshot) or on their name in the Parties HUD (4 on the screenshot).
You can use the Tab key to cycle through visible players.
If you wish to observe without centering your view on a single character, find one of the small camera icons on the map and click on it (a on the screenshot). Your view will move to that point.
You can also choose the flag stand for observation (b on the screenshot). The flag will change colour depending on which team currently controls the flagstand.
Turn on the Auto-Camera feature (click the check box; 2 on the screenshot) to let Observer mode take over for you. Auto-Camera will move from camera to camera (and sometimes from player to player) to let you follow the action with ease.
Press the O button while in Observer mode to see the score window (3 on the screenshot), which tracks the Health and Morale of each team throughout the game (use the drop-down box c to switch).
The time elapsed since the match started is shown in the top middle of the screen (5 on the screenshot).
The health bar of the character you are observing will display at the top of the screen (6 on the screenshot). If the character uses a skill, the skill monitor will display beneath the health bar.
While in Observer mode, you can chat with other observers using Observers Chat (7 on the screenshot). Players in the match will not be able to see observer comments at any time.

http://eu.guildwars.com/pvp/article/observer_mode/