It appears that Turkey is not the only country blocking YouTube. However, reportedly site redirected to picture of the King at one government web site but this redirection doesn't work any more.

Link to BoingBoing report:
http://www.boingboing.net/2007/03/09/youtube_blocked_in_t.html

including new information, i.e. YouTube is accessible now and maybe it was a problem of one specific ISP.