I just took a CL Nomad Zen I bought a year ago back to Compusa. I had bought the extended plan and figured no big deal.
I walked in, handed him the bare unit (none of the cables etc). Told him it was dead. He looked up the serial number, threw it in a bin, and gave me full refund + tax in store credit.
He didn't even try to turn it on or anything. VERY hassle free. I walked out with a new 4g 20 gig w/ a 1 yr replacement plan for $40 over waht I paid for a Zen earlier this year. The Zen was ok, but big and fragile, not to mention the players interface sucked, as did the software interface.
Total turn around time from dead Zen to new iPod = 20 minutes.
Hope that helps you out some.