Oolong teas fall between Green and Black teas on the oxidation scale. While this may seem an insignificant variable, it yields a dizzying array of tea styles and flavors. Literally translated, Oolong means "Black Dragon".
Oolong teas vary greatly not only in taste, but in preparation time. Darker oolongs (highly oxidized) generally need very hot or even boiling water to get the leaves to open up and release their oils. Greener oolongs (lightly oxidized) can take water just above the temperature at which green tea is brewed - around 185 or 190 degrees. Steep time is really to your preference; oolongs are designed to be infused multiple times, so whether you do two steepings at 4 minutes each or 10 at one minute is really up to you!