I recall reading something a few months ago to the effect of: At least one-third of the people entering the work force today have at least one tattoo or piercing (excluding ear piercings).
Body mods are so common now days that I don't think there are many people who would be offended or shocked by someone who showed up acting professional and looking well groomed (hair combed, shirt tucked in, clothes clean) who also happened to have some visible tattoos or piercings.
But like anything, there can be excess: As an employer I could probably tolerate colored hair, but not a mohawk, at least not on someone who dealt directly with customers. Any more than two or three "unusual" piercings and I would probably have to draw the line.
-John
