Amazon.com and .co.uk and Air Lingus are doing it as well (for departures from Gatwick).
AL is Irish, so that does compute, ;-) however Amazon should be above playing those games. On a $20 purchase at amazon.com, if I let them do the conversion into Euro, I'd pay about $3 more.

I'm not going to ireland very often but me buying a DVD at Amazon happens rather frequently. :-)

I was offered the "choice" of paying in dollars or pounds at Roseberry Hall, a London School of Economics accommodation, last week.

When I say switched buttons on an ATM I mean that they ask you if you want to be billed in
"Dollars - Yes or Euro - No" and then they have the No button on the left and the Yes button of the right to confuse you. It's a slight difference but I have almost made the wrong choice because of it.