Toro is right--in the truest sense of the word, the Eagle is not a fly by wire jet. But...
Actually, the C model does have a simplistic fly by wire system integrated with the standard hydromechanical control system.
When you move the stick a bunch of pushrods do their thing through an integrated assembly that compensates for changes in airspeed, temp and pressure. That system will give the pilot the same amount of G for a given amount of stick travel regardless of speed (as long as the aircraft is capable of pulling that G). For example, three inches of stick travel (just an example--not exactly) will give you 5 Gz at 600 knots as well as 300 knots.
The fly by wire system is called CAS--Control Augmentation System. It centers around a stick force transducer, which is a square-ish box located just below the stick grip. When a pilot puts pressure on the stick, the transducer senses that pressure and sends electrical inputs through the threee CAS channels to the stabilator actuators. They in turn move symetrically for pitch and asymetrically for roll. CAS is not self-sufficient for all needs, however; inputs from CAS alone are not enough to fight with, but it will provide enough controlability to get home if the stick is frozen in place by FOD, for example. Working together, the CAS fine tunes the hydromech system in all flight regimes.
The CAS is pretty sensitive, too. One of the more common mistakes of new Eagle drivers (and old guys that haven't been to the tanker lately) is getting tense while refueling. That leads to gripping that ol' stick too tightly, which in turn causes the jet to get "the jitters"...the jet just moves around in a jerky fashion, not really going anywhere but not stable either. The cause? Mr. pilot is inadverdently making CAS inputs from his death grip on the stick, even though he isn't actually moving it laterally or longitudinally.
The combined flight control system is a thing of beauty--the Eagle flies like a Porsche handles on the road. Between the standard flight controls and the CAS channels, the aircraft is a VERY nice handling machine.