No, this is not a joke.
"Etihad Airways announced that five flights between Abu Dhabi and England were canceled Thursday."
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http://us.cnn.com/2010/TRAVEL/04/15/...ex.html?hpt=T1
Latest news is that British airspace is closed until 6am on Friday, but if the ash persists, that could last longer
(Thought I'd post this as a separate thread so people in AD have a single place to look for info we may hear)