At the weekend my 4 year old niece said the words that all knitters want to hear. Not "Lizzy, can you make me some cosy bed socks?" (although she said that too) but "Lizzy, how do you do your knitting?". It's not quite an outright request to teach her how to knit but it's close enough for me to pick up some chunky yarn with a decent amount of pink in it and suitable sized needles to have on hand should she express such a wish again over Christmas.
She's already got the hang of baking (at least she knows about stirring and licking the spoon afterwards) so I think she's ready to start playing with yarn.