Despite what narkeeso said, a font only has one baseline. All of your icons should sit on that line to be consistent. Some icon fonts try to center the icons vertically but this causes more problems than it solves and you can always adjust the vertical position of the icon relative to surrounding characters using the vertical-align property.
I tested the baseline in the template heavily for that article and it is very successful across browsers. You may wish to match the X-height to a common font like Arial, however. This can be done in the Font Squirrel converter.
