I hate to pop WSUs bubble, but I am not a big fan of sweeping generalizations.
There are some key differences between 1.2 and 1.3 that may be very important to some people who rely on these boards for research.
Source here is the Wikipedia article:
HDMI 1.3 was released June 22, 2006 and increased the single-link bandwidth to 340 MHz (10.2 Gbit/s) which is roughly double the older standard.
HDMI 1.3c is the current version. It was released on August 25, 2008 (ie is probably not in the stores). 1.3c has no effect on HDMI features, functions, or performance - meaning that 1.3a is what you are looking for.
Here is a summary of the key differences:
Deep Color: 1.3 supports the deep color format. Agreed there is no software available right now and you also need a deep color capable monitor
xvYCC: this is another video signal specification
Both of these are made possible by the increased bandwidth. Color depth doubles from 24 to 48 bits.
Auto lip-sync: this is a truly useful function. took me exacty three seconds to select it - everything is in sync all the time. Not sure what the work around is for older HDMI formats, obviously there is one.
Dolby TrueHD bitstream & DTS-HD Master Audio bitstream capable
These are the uncompressed lossless formats that everyone on this board is raving about. There are two workarounds, both of which depend on getting an appropriate BluRay player with suitable capabilities.
1) some BluRay players can do the decoding locally, you will then have to run 6 or 8 RCAs to your receiver to hear the decoded signal plus running an HDMI cable for video if you want 1080p.
2)Some Blu-ray players can decode all of the audio codecs internally and can output LPCM audio over HDMI. Multi-channel LPCM can be transported over an HDMI connection and as long as the AV receiver supports multi-channel LPCM audio over HDMI, and supports HDCP, the audio reproduction is equal in resolution to HDMI 1.3 bitstream output.
Note that at present this is only an issue if you own or plan to own a BluRay player. If you do not have a BluRay source there is no advantage to the 1.3 standard.
Wsu is right about one thing. Standards are pretty firm now with the technology being ahead of the consumer for the time being - my guess is at least 5 years given the adoption rate of BluRay to date.
A contributing reason is that the software people (the studios) have not yet caught up with the capabilities of BluRay. There is some question about whether the mass market will move on to BluRay - DVD looks darn good on the right player.
Of course the economy is not helping much either...