I've done this with an Infiniti. If you look at your lease online, there is a payoff quote button. If your car has held it's value (which as of today, based on some of the auction data, it still has) then you can hand it over and walk away.
As an example, my payoff is almost $22k. If you call them up, they'll look up the current value (I don't know what they use to decide this). If the value is more than $22k, then they'll take it with no cost. It sounds like Gonewild is in this situation, he just has to be current on his payments, they can also charge for above wear and tear, hence why he still has an inspection scheduled. It's actually really straightforward.
If the value is less than $22k, you can pay the difference (plus tax). So if they decide its value is $20k, you would pay $2k + tax to turn it in, plus any wear and tear.
In California, it is the law that they are required to accept an appraisal as the value of the car. When I called for the Infiniti, my payoff was $29k. Inifiniti said it was only worth $26k and so I hired a license appraiser for $200 and told him I needed a wholesale appraisal. He came back at $28,500 and I turned in the vehicle with the appraisal and $500 + sales tax. So I saved $2k by hiring the appraiser. This is another option for those in California if Nissan says their payoff is higher than the value.