'i' just gives you the device ID (which you can already get from the CLI).
Edit:
Actually, after fiddling with DFU I stumbled on the proper answer which is to use "s" in listening mode.
Also, after updating to 0.4.4, you can type "v" to get an output like this: "system firmware version: 0.4.4"
A more detailed discussion can be found here:
Note that to pretty-print the JSON output you will want to use the part in brackets/braces only. (Omit the leading "p":6,"m": part.) As of 0.4.4, it looks like they wrapped it more properly so you don't need to omit any of the output!
Also, for 0.4.4, the version number encoded in JSON shows "5" (not surprising once you let go of the idea that any of the digits in x.y.z should map to that single digit... "v" is effectively the decoder ring for that now).
I see my newly arrived one has some older software versions than I expected. Interesting to see how it changes when I flash new software today.
FYI, another handy viewer for JSON is found at http://www.jsoneditoronline.org/ Ensure you use the "expand all fields" button to see everything.