Applied, got bag & box in the post and sent it off yesterday.
I’ll be happy to get a perfect, shiny replacement 1GB one back to abuse for a few more years, but will be equally happy with a more recent replacement.
Given how complicated opening one up and replacing the battery is (they go together easily on the assembly line but opening one without damaging it is incredibly tricky), I can’t see how they’ll refurbish hundreds of thousands of the things in any reasonable time. Unless they kept back huge warehouses of them, they won’t have units available to ship out. They’d need an army of very skilled people to do it, they’ll need a load of replacement backs for engraved models, and take the time to do full tests on everything sent out. It would rapidly get to the point where just sending out a refurb current (or previous gen) Nano is more cost-effective. Nano sales seem pretty flat these days anyway, they probably have a stockpile of them somewhere.
Apple will be keeping tight-lipped because they don’t want it reported as “hey, send in your old one, get a shiny new one for free!”.