Wizzair 1898, an A320 from Keflavik, Iceland to Wroclaw, Poland declared an emergency about 20 minutes after take-off and returned to Keflavik due to an onboard fire.
http://http://www.ruv.is/frett/ekki-...starfi-um-bord
(apologies, Icelandic only).
Later news reports indicate that an electronic cigarette caught fire and was thrown either into the toilet or into the lavatory. No word yet whether the crew had to extinguish the fire.
Do any operators really allow the use of electronic cigarettes onboard?