One cool feature of the juniper junos CLI is that all the CLI commands have an option for XML output, making parsing of the CLI output in scripts a little more sane.
Nice ideas, but the inertia of existing unix tools is going to be hard to overcome, and a system isn't much use until all your common tools support it (or at least don't break it).
I talked some folks into using JSON output for a tool, and am now in the midst of fixing both ends so that the output is valid JSON, instead of a newline delimited file with JSON on each line.......
Both http://acko.net/blog/on-termkit and http://blogs.perl.org/users/rocco_caputo/2011/05/apppipefilt... seem to fit what I was thinking of, but I'm sure there was something else.
Nice ideas, but the inertia of existing unix tools is going to be hard to overcome, and a system isn't much use until all your common tools support it (or at least don't break it).