yes, you can, if you have the eCognition software (you can find it here on this forum).
eCognition creates images segments (trees, buildings, roads or water bodies) but even so, it will be hard to make a very good clasification map, because your quickbird image has only 3 layers (green, blue, red).
For example, if you have an aditional layer, let's say infrared (NIR) you can use this to better classify vegetation vs buildings or water !
So, good luck my friend !