Is the Zune on its last legs? Buried in Microsoft’s terrible earnings report yesterday was news that revenue from the MP3 player plummeted $100 million compared to last year, or 54%, “reflecting a decrease in device sales.” Microsoft can’t just blame the economy, either; sales of rival iPod are still rising. The release states that Microsoft will continue making “significant investments” in the Zune, notes Podcasting News. But for how long? (More Zune stories.)