This might be a dumb request, but I know at least one other IDE (jEdit) that has this and I liked it...

The PEAR coding standard recommends a line length of 75-85 characters.

It would pretty sweet if we could have a visual marker that sat at some configurable number of characters from the left side of the editor. This way a person could see roughly how long their lines are. I do NOT want it to auto-wrap at that mark, this is simply a very subtle style indicator.

If this is possible, it'd be best if it were a vertical line like jEdit. If I have to look outside the editing window to get the number of characters or at the bottom of the screen (ala vim's default setup), that is a very poor workflow and reduces the utility of the function altogether.

Half of my team use vim/emacs and they throw a fit if people make super long lines

Maybe this is in there and I haven't seen it yet, but I looked through the menus pretty thoroughly. As various frameworks and PHP projects get closer to converging upon an agreed-upon coding standard, you are going to keep getting these sorts of requests I think

PhpED has this since ages
It's called "Right margin" and you can find it under Tools > Settings > Editor > Appearance

Make sure the "Monospaced fonts"-checkmark at the top right is activated and then the option at the left bottom will become available.
Enter the correct number of columns, choose a color and voila.

FYI: It seems the current build 5958 has a bug that resets the color to white every time you restart the editor. I have already reported this.

Ahh, thanks! I had toggled it on but the color was set to white!