From hdmi.org:
The HDMI 1.2 specification also adds features and capabilities that increase HDMI's appeal for use in both the CE and PC industries. Specifically, the features and modifications for HDMI 1.2 include:
* Support for One Bit Audio format, such as SuperAudio CD's DSD (Direct Stream Digital)
* Changes to offer better support for current and future PCs with HDMI outputs, including:
o Availability of the widely-used HDMI Type A connector for PC sources and displays with full support for PC video formats
o Ability for PC sources to use their native RGB color-space while retaining the option to support the YCbCr CE color-space
o Requirement for HDMI 1.2 and later displays to support future low-voltage (i.e., AC-coupled) sources, such as those based on PCI Express I/O technology