A Microsoft XNA Framework Developed stated at a Microsoft forum that no code changes are required to support Xbox 360 HDMI.
Microsoft hasn't officially announced it yet but it's believed that the company will soon unveil its black Xbox 360 Elite console which will have a 120GB HDD and HDMI support.
In a question posed under Microsoft’s Developer Network, a user asked in the XNA Game Studio Express section if any code changes are required to support the HDMI output on the revised Xbox 360. Shawn Hargreaves, XNA Framework Developer at Microsoft, replied simply with “No changes required.”
The comment by Hargreaves marks the first comment from a Microsoft employee acknowledging the HDMI output on the Xbox 360. Furthermore, his reply insinuates that the new HDMI output options will be completely transparent to developers, leaving the video duties completely up to the scaling hardware inside the new Xbox 360.