This link lays out what changes they have included already...
http://www.support.dlink.com/faq/view.asp?prod_id=3269&question=DSM-750
What changes have been done to the latest firmware for my DSM-750?
Release Notes:
Version 1.02:
* Added support for Matroska H.264 video files.
* Added support for FLAC audio files.
* Enhanced the support for WMV HD files.
* Remove the Yahoo Music icon from online services.
* Added support for playback of videos using the MediaMall PlayOn service.
* Control of SRT subtitles improved in MediaLounge mode. (User can control subtitles on/off, position onscreen, delay or advance subtitles for better sync, font color and font size.)
* Support of SRT, SMI, SSA, ASS, Subviewer1 & Subviewer2 subtitles when played from a USB drive.
* Support for WPL playlists on USB drives.
Version 1.01:
* Support for 1080p TVs and video files
* Look of the Home page altered to improve navigation & readability
* Online Media icon added to the home page
* Support for Live365 Internet Radio service
* Remote control support changed to support Xbox 360 remote
* DVR-MS playback A/V sync issue in MediaLounge mode resolved
* Control point (aka "slave mode") access enabled for playing video and music files from a compliant UPnP server
* Browsing music & video media files/folders now supports only List mode (no thumbnail browsing).
* Photo files/folders supports browsing by thumbnail or list mode
* "16:9" and "4:3" renamed "Widescreen" & "Normal" in A/V Settings Menu
* Default device name is now "D-Link DSM-750"
* Audio tracks button improved to support multiple audio tracks in supported video files
* Entering a wireless security key is now readable until entered
* Reduced the amount of marqueeing text in the music player page
Version 1.00:
* Shipping firmware