Paula,
I'm not sure if this is exactly what you want but you can set a vertical
line for the current date or the status date by going to
Format/Gridlines and selecting one of those two dates from the list on
the left of the gridlines window. Set the line type and color to suit.
You can set the line for virtually any date by temporarily changing the
current date setting in the Project Information window under the Project
menu.
As far as naming a date line, you may be better off using the draw tool
to simply draw a vertical line at the date you want and then applying a
text box. You should be able to "attach" the drawn line to a gantt
object so it will move with the chart.
Hope this helps.
John