D-Link has released the first firmware update for their DSM-750 Extender.  Based on the release notes it appears that most if not all fixes in the new version 1.01 apply to the MediaLounge software and not the Media Center Extender aspect of the product.  That said it does appear to add 1080p output as an option which should apply to both the Extender and MediaLounge modes.  Other changes are below, you can download the updated firmware here and upgrade via the front USB port on the DSM-750.

• 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 Rhapsody music service
• Support for Live365 Internet Radio service
• Support for vTuner 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