I have very long hair and just tie it back, it's no problem at all. I have a low pony tail as I think a high one would bob about too much like a horses tail and that would get on my pip.
I sometimes tuck my pony tail down the back of my running top, not directily onto my back but ontop of my t shirt but inside my zip up jacket...I have recently started running so dressing for the cold at the moment. I would imagine in hot weather I would put it into a pony tail than pin it up competely out of the way. I do see woman running with their hair flowing loose but personally that would drive me nuts.!!
Mine has to be tied up otherwise i would be concentrating on keeping it out of my face rather than running!! i just pin back my fringe and put my hair up in a pony tail and i am ready to take to the road.
when I had long hair; (well, when I had hair !) I used head bands before moving on to bandannas. Hair still gets in the face when there's a tailwind though.
Mine's a bit below shoulder length and I put it back in a ponytail, and use a hairband to keep back the layers that aren't long enough to get in the ponytail.
I only plait my hair when I go skiing - I find even a ponytail gets tangled in a long day's skiing.
I've got long hair and I tie it in a low pony tail and plait it. As runda said it swishes about too much otherwise! Also, in windy/wet weather it doesn't get knotted.