As expected, Sprint has announced the SPH-m620 "UpStage" dual-faced musicphone today, giving Sprint a decided "wow" factor in its lineup -- for the moment, at least. Manufacturers seem to be turning to unusual form factors in an effort to gain some differentiation in a crowded high-end and specialty phone marketplace, and the UpStage fills the bill nicely with a full side devoted to traditional phone activities -- "calls, text messaging, and contact management" to use Sprint's verbage -- while the entirety of the flip side takes the form of a traditional MP3 player; a button press switches between sides. Naturally, the phone offers a microSD slot for up to 2GB of external storage, a 1.3 megapixel camera, and stereo Bluetooth, while an included 3.5mm jack adapter lets folks use more traditional headsets if they so choose; even cooler, incoming calls are announced via text-to-speech while you're jamming out. Also included is a Music Manager app for sideloading tunes to the phone via USB and a unique "battery wallet" boosting the phone's stamina for playing music up to a solid 16 hours or 6.3 hours of talk time (up from 2.5 hours talk time without) -- you sacrifice a bit of girth from the phone's normal, svelte 1.73 x 4.07 x 0.37 inch form, but for music junkies, the tradeoff may be worth it. Simultaneously with the phone's release in early April, Sprint will be offering 99 cent over the air (nice!) music downloads good on its entire Music Store catalog, which we reckon is just perfect for a phone of the UpStage's nature. Look for it to hit shelves for $149 on a two-year agreement with a $50 rebate available.