A column width for each line?

I wonder if any of you have a policy on column width when writing code.

Ruby and Ruby on Rails don't seem to have set any rule.

Merb says "80 column line width except in exceptional situations"

* What's your personal thoughts on column width? Needed or not needed?
* If you work alone, do you have a personal policy?
* If you work in a team, do you have a guideline?

I feel 80 is too narrow. Even when working with a notebook, people
have like 13 inch display.

* What's the optimal width if you set?

I don't have much programming experience, so I would like to hear from you.