How to show vertical line to wrap the line in Vim?

New in Vim 7.3:

‘colorcolumn’ is a comma separated list of screen columns that are
highlighted with ColorColumn. Useful to align text. Will
make screen redrawing slower. The screen column can be an absolute number, or
a number preceded with ‘+’ or ‘-‘, which is added to or subtracted from
‘textwidth’.

Example from the docs:

:set colorcolumn=+1        " highlight column after 'textwidth'
:set colorcolumn=+1,+2,+3  " highlight three columns after 'textwidth'
:highlight ColorColumn ctermbg=lightgrey guibg=lightgrey

You can use absolute numbers as well:

:set colorcolumn=80