Interesting...hadn't occurred to me that she died and was reborn again. Also the idea tha maybe Willow traded her life for Buffy's? Except I don't think Willow knew the future besides what Buffy told her and the snake goddess went out of her way to tell Willow not to look at the future.

There's a rather good review of all of this in aycheb's journal that you should check out. She actually did a better job of explaining where I think Whedon is headed than I did.