This actually happened to me right after 9/11. I was flying to Asia and was were not allowed a carry-on. The plane had to divert to San Fran. We were given free hotel rooms, and a toiletries kit but not our luggage. The kit had a box of Woolite, and we were expected to wash and air-dry our socks and underwear in preperation for the following morning's 12 hour flight.
So far it's UK. I flew back to the States from Copenhagen a few weeks ago, about two weeks after the flurry at Heathrow, and we were able to keep our carry-on bags - just without liquids or gels. So it doesn't seem to be the rule in the rest of Europe.