In reply to mypyrex:
The card machines I have used in the past (15years ago) required a "cashing up" type procedure at the end of the day which sends the finalised payment request to the bank that provides the machine if not done before close of banking hours it will drop to the next day. Some people who dont take a lot of card transactions may only do this every few days, having said that more modern machines probably dont need this procedure anymore. The bank then processes this payment with your card issuer. So delays can creep in due to procedure of different banks (they may bundle up foreign currency transactions to reduce conversion losses) and even timing issues (transaction arrives just after a batch window)
Ive found quite a few times in europe that transactions have taken a week or so to show up.