Supported video formats include MPEG-4 ASP (DivX, Xvid, Nero Digital, etc,...), MPEG-4 AVC (H.264), H.263, and WMV. Audio support includes MP3, AAC, WMA, and OGG. Besides playback, it can also be used for simple video recording and editing, and even has a built-in FM radio.
Although the iPhone has arguably made a bigger impact in the smartphone market than any other single product, it would be foolish to say Apple is the undisputed leader. In fact Research In Motion (RIM), makers of the Blackberry line of phones, has benefitted greatly from the increased visibility of the entire smartphone market due to Apple's success and they still control nearly 50% of the market.
While not as successful as either RIM or Apple, Samsung's share of the market rose from just over 5% to more than 8% at the end of last year.