Phil Sheridan of Philly.com makes a good argument for trading or releasing Sheldon Brown.
He cites the Eagles experiences with Terrell Owens and LIto Sheppard. Those didn't turn out well.
The best argument against trading him is the trend you would be starting. Once players believed that they could force a trade by complaining about their contracts, Joe Banner and company would have a line in front of their door.
There are going to be players complaining about their contracts as long as the NFL exists. It's not wise to treat them all the same. It may see fair but it's wise.
You treat Superstars who you can't replace one way and you treat guys who you can replace in another way.
If they can replace Sheldon Brown with a player at the same or better level then they should give him his walking papers. If they think the dropoff is too big and will clearly hurt the football team, then they must consider keeping him on board.
They will have to decide whether it's better to keep Brown on the squad despite his unhappiness or trade him and replace him with a lesser player.
After spending a bit of time mulling over this situation, I say go with Ellis Hobbs and trade Brown.