[sorbits]

Last I was in an Apple store they put a sticker on the purchased goods (this was before the self-checkout).

I assume the sticker was proof-of-purchase (as receipt was being emailed).

[X-Istence]

They still do this with anything large they go get from the back of the store (new computers, new laptops, iPad's and the like) but not with stuff that you can grab off the shelves.

The stuff they grab from the back of the store still has to be paid in person with someone that has an iPhone with card scanner... no self-checkout there yet :P