Answer:
well this depends on what moving average you are using. for example if a stick is above its 200 simple moving average (a very important time frame) you can saftly say it is in an uptrend (careful it could always reverse trends). Moving averages can be use for trading to ex. http://www.squidoo.com/swing-trading-tutorial
for short term trading like swing and day trading you should look at smaller moving averages like the 10 period, and 50 period, which are widely used.
Caution! remember there are 2 moving averages in trading, a simple moving average and an exponential moving average, make sure you have the right one.