On a personal level, I'm sorry to see Panthers CB Ken Lucas go. He was a class act -- demonstrated most vividly by his forgiveness of WR Steve Smith after getting sucker-punched in the nose during training camp. Here's Charles Chandler's story about Lucas's release.
On a professional level, however, it was time. Lucas was a liability for the Panthers late in the 2008 season. Teams would throw the ball time and again at him. And while CBs Chris Gamble and Richard Marshall certainly weren't immune to getting burned, either, it was Lucas who was MFT (Most Frequently Toasted).
It's obvious Carolina really doesn't want Lucas at this point, and that's the right decision. Even after his release, he still counts more than $8 million in "dead money" against the salary cap this season. That's a ton.
But Marshall, honestly, is a better cover corner right now than Lucas. This position just became a spot of bigger need in the NFL draft for Carolina, too. The nickel corner in the NFL is practically a 12th starter on defense, so Carolina now needs to find one of those on its bench or at a modest price to defend against the 3-wide receiver offenses of today's world (New Orleans, Arizona, etc).