A number of readers are sending word that the blogosphere and Twittersphere are alight with reports of Microsoft's new block on messages containing YouTube URLs. Both MSN Messenger and Windows Live Messenger reportedly implement the block. One blogger sniffed the network to discover that such messages receive a NAK from Microsoft's servers. Microsoft has been blocking messages by keyword, as an anti-phishing measure, for some time, but *.youtube.com would not seem to provoke much worry about phishing. Instead, as B.E.T.A Daily speculates, "This block seems to be related to the recent launch of Messenger TV in 20 countries which allows for sharing video clips from MSN Video on Messenger." Hard to get away with in an arena where you don't enjoy a monopoly.