Earlier in the week, Microsoft has sent out a memo to all employees to stop referring to the design language it uses for the Live Tiles and the interface of Windows Phone
, for instance, which later spilled over to Windows 8, Office 2013, its web services and so on, as "Metro".
The new UI design of Microsoft has been inspired by the clean and easy to perceive public transport signage you see in the thumb on the left, that's why they called it "Metro".
The memo said that "discussions with an important European partner" have resulted in the decision to "discontinue the use" of the word across the board, and everyone must comply ASAP.
"Working on a replacement term", clarifies Microsoft, "and plans to land on that by the end of this week" The employees should now call the Metro UI the "Windows 8 style UI", until marketing comes up with something cooler. What provoked the whole thing we can only speculate, but some wager to guess a trademark infringement threat is always a good candidate these days.