Robert M. Gary wrote on 9/27/2005 14:07:
In the case of the A320, or the 737, they can both land with a full load

of fuel.

Then why did Jet Blue fly around for 3 hours burning fuel before
landing back in LAX?

The last link provided by Kev has the likely answer:
"The primary reason to burn off the extra fuel was that a heavier plane
has a faster landing speed. Since a slower airspeed on landing was the
objective in this case, the course of action was to lighten the load by
burning off some fuel and when landing, lower the nose gear at as slow
an airspeed as possible."

-Joe