(replying to myself after further digging because i need this to work on latest raspbians)
did a number of fresh-imaging of raspbian and booting with various wiring combinations ... turns out all versions sometimes work and sometimes don't, though the 2013 version seems to work less often. it depends how is wired:
what *always* works:
power the raspberry pi with a usb cable with plenty of power - some of the cell phone adapters do not seem have enough power.. try powering it from a computer usb port just to make sure it works .. they seem to have enough power
what does not always work:
* lower-powered usb converters (e.g. cell phone or bluetooth chargers)
* the powered usb hub powers the raspberry pi. yes i mean the usb hub connecting to the power of the pi, and *also* one of its usb outputs, and then the keyboard/mouse adapter into the hub. this sometimes works on the older raspbians. maybe i need a higher-output powered usb hub. though it seems like a usb loop, i am assuming the raspberry power only caries power not data. anyhow this works sometimes.
in other words, "is it plugged in? properly?"