Was thinking about this this afternoon, but assuming that Apple are using Toshiba drives, then I guess the new 160gb drive is the MK1626GCB.
And that drive has a different interface from the older iPod models in this case, CE-ATA according to this piece.
So, my guess is not. My last attempts at swapping a hard-drive in an iPod worked but left the case damaged. I'm not going to try it with my 5.5g 80gb one; I'd rather sell it and get a new one I think.
I'm assuming you mean Coverflow performance. That might be due in part to the slower interface speed of these new drives.
Anyway, it seems like the answer is 'no' due to not being PATA drives. However, if another manufacturer releases a PATA 1.8" drive with the capacity, then it might be worth considering for those who feel a little brave.