Any ideas what this bamboo is ? It was given to me today by a friend who had no idea what it was either.

Bit better picture

It's Miscanthus sinensis "Zebrinus" colloquially known as zebra grass. It is a grass but not a bamboo, but it's very nice nonetheless. The stems die each winter, but to me it still looks nice when dry in the winter. So cut it down in late winter (something you'd never do with bamboo) and let the new green shoots grow from there.