Your question begs another question - what is your audience? If you contributing to a specific project, you may find that it has its own guidelines or rules, so it would therefore be a good idea to enquire. If, on the other hand, you are writing for yourself, write it in such a way that you can read (and understand) it when you come back to it later.

Personally, I cannot understand why so many insist on 80 column lines. How many programmers nowadays still use 80x24 terminals? As I write stuff primarily that nobody else will see, I tend to use 132 column lines. This is perfectly readable in gvim on my 21 inch wide-screen monitor (and I use big fonts) and never wraps when the editor is maximised - which it always is. (And it will still print correctly on an old wide-carriage dot matrix printer ;-)

I also use a 2 column tab setting - this can keep lines to a more sensible length when there are many levels of indent.

To conclude, I'd say work to what your audience wants/expects and if that audience is just you, go with what you are comfortable with and what suits your monitor.