I never thought of that... but its a good point!!! I think the Steelers would trade Polamalu for LJ straight up right now even though they are high on willie parker..... so I must agree with you.....
Back when they made this trade, I was mad as anything, as I wanted to see LJ as a Steeler knowing Bettis was about to retire and not knowing Parker even existed yet.
However, considering what happened in 2005/6 with the SB win, I think you'd be hard pressed to find a Steelers fan that would want to tinker with how it went down.
However, considering the coaching change in 2007 to a coach more versed in the 4-3 defense, Polamalu might end up gone soon, or at least a more useless safety than he is in the 3-4. Talk to me in two years, I'd trade LJ for Polamalu pretty quick by then I bet.