CIE stands for..... well it's a French acronym for the International Illumination Commission, which is a body that sets standards for the definition of colourimetry of all TV systems.
The chart is a method (there are a couple of different chart types and layouts) for showing the relationships between colours.
D6500 isn't actually the same as 6500K, the D6500 point is slightly off the black body curve and the D is simply an indication of a specific point (there are an A, B, C and E at various points) and the 6500 is that it is pretty close to 6500K.
There are some variations in how TV sets are set up, for example;
Black and White material should actually be shown at 5600K which is the native temperature of a Xenon Arc lamp
The Japanese do indeed set a very high colour temperature, often around 9200K, as this helps the oriental skin tone to look more natural on screen (it also makes whites bluer and therefore 'cleaner')
Tungsten lamps are around 3900K, so any projector used on-screen in TV studios will usually have this temperature available.
The main difference though between US and European TV is the colour of the phosphors as specified by the EBU for Europe and SMPTE for the US. What they are setting are the points on the CIE graph for the pure colours of the Red, Green and Blue phosphors or filters.
If you took an image that was taken with a camera following one standard, and showed it on a TV from a different standard the colours would not match (Red could be a bit orange or a bit mauve for example)
This isn't massive for PAL and NTSC (significant though) but it gets pretty big when we get into HDTV and D-Cinema, both of which have much bigger colour gamuts (The area between the three points) Consequently conversion between any of these formats (and of course PC colour space) is necessary for proper colour reproduction.
It's worth noting that the colour Gamut of a D-Cinema projector is larger than that of 35mm film!
All our standards and resolution conversion kit obviously have had this kind of thing for years, but it's only now with the advent of D-Cinema and widespread commercial use of HDTV that it is being understood in the wider industry.
Hope this helps without being too technical !!!