Sennheiser has announced it will show its new MM50 iPhone headset this week during the Mobile World Congress in Barcelona, Spain. The MM50 iPhone is a wired stereo headset that features an in-line microphone. Further details, such as pricing and release information, have yet to be announced. In addition to the MM50, Sennheiser also introduced several new Bluetooth products, including the MM 200, a Bluetooth stereo headset, the BW 900, a wireless office…