A B757 crew declared an emergency and diverted after the FUEL CONFIG annunciator alerted to a 4;000 LBS fuel imbalance at cruise.

Narrative

At cruise altitude FL370 steady state operation; tank to engine fuel configuration. FUEL CONFIG light illuminated with associated EICAS fuel configuration. After analysis and reference to the Fuel Configuration irregular checklist and consulting Maintenance we felt the issue could not be resolved in flight. We were also now at a 4.0 fuel imbalance and it was increasing at a rate of 6.0 thousand PPH. Diversion airports were reviewed and with consult of Dispatch the decision to divert was made. Emergency was declared and direct to the diversion was initiated. Cabin was advised of issue; cabin advisory communicated to Purser. Landing was normal with left wing heavy correcting. Taxied to ramp; waited 20 minutes for gate. Customer Service made accommodations for passengers. Captain called Maintenance and Dispatch to debrief issue. The Flight Duty Manager was called shortly after for debrief. Side bar; post flight I was informed by Purser that other Crew flight attendants had been called by their Crew Desk while we were still taxing and in a sterile operation. The nature of this call was not related to safety but a heads-up about reassignment possibilities. I was not pleased that this was going on while we were still operating a distressed aircraft. I must voice my strong objection to this cell phone/computer use on aircraft by working crew. This is an issue that little to no guidance has been given from the Company. A policy must be established and unforced by Captains; Pursers and Management. There is also the issue of the passengers with INTERNET devices getting information on our diversion prior to us making a PA announcement. How does this information get leaked so fast? Why is this information being leaked before the flight terminates? This puts the crew in a difficult situation as far as communication is concerned.