4.1 Line Length
Avoid lines longer than 80 characters, since they’re not handled well by many terminals and tools.
Note: Examples for use in documentation should have a shorter line length-generally no more than 70 characters.
If I understood correctly (I may be wrong), one goal of this rule is consistency. I used to think that 80 was silly, but being able to go through source code written by a dozen different teams over last 7 years and not needing to re-size my window is a really nice thing. Consistent column width helps with the pace of reading code. Since I mostly worked with large monitor, I also realize that we are wasting lots of precious space. Consistent column width of 80 is simply too little. I personally use 120 unless the project I work already finalized a column width, in that case I go for consistency. One more reason people give for still using column with of 80 is that now days they are working with multiple files at once. For example, if you use standard column width you can fit couple of files across a reason and can compare them line by line, which I believe is real benefit. You can even do a three-way merge inspection on one screen without scrolling sideways. By the way this should not be done at cost of excessive wrapping. I understand that consistent columns make it easier to scan and read through text but it doesn’t mater whether it’s 80 or 120.
On closing note, I would say that consistency is nice and you must go for it but 80 or even 100 is too short. Many developer could probably live with 120 or even 150 though. Our modern wide screen high definition LCD monitors can easily handle more. It is much more readable then the excessive wrapping because I personally find it much harder to read a wrapped line than just seeing the whole thing in one line. Of course this is just preference and others will feel different.