In reply to sammwatkins:
You should have a comment box.
personally IO don't think it'll work because:
1) walkie talkies have a limited amount of frequencies and you'll just get loads of climbers using the same channel (I use walkie talkies at work when writing electrical reports on buildings and we have other people using the same frequency. but in climbing we are all using the same calls and confusion could occur)
2) if you are climbing on some hard rock (dense rock that won't allow a signal to pass) the radio signal maynot get to the other person. if you are use to climbing with a regular climbing partner you can feel the rope what they want.
3)it is another piece of technology to go wrong.
4)climbers are tight and don't want to spend money.