From personal experience it depends on the employer, I have had employers that don't mind my tattoos and those that complete hate them. Here's a few situations from both perspectives:
My current employer loves tattoos and has quiet a few himself, he has a simple rule about them. He doesn't care what they are or where you have them, but if they're inappropriate they must be covered up while at work. If you ask me that is a very fair rule, nobody wants to walk around a work environment with someone having racial or sexual content showing on their body (I've worked with people who have both).
Now for the not so good side, at the start of the year I had an interview with a tech company in London (will not name for obvious reasons), my friend works there and encourages me to apply so I did. I went down two days early to visit him and he told me that I should cover my tattoos during the interview. Mine are on my arms and are fairly easy to cover. I went into the interview and within five minutes he asked me "Do you have any body modifications? tattoos, piercings etc". I thought no reason to lie and said yes I have tattoos. It was at this point he said to me "Well you might as well leave, I am not going to hire someone that does that to their body". I was pissed.
I've always seen the work environment as a place that people should always be comfortable in and have as little as judgement as possible or none at all. I personally have no problems with tattoos, piercings or any other form of modification. It should always be about the persons skill set and what they can bring to you as a business. I understand that some companies have an "image" to protect and would rather not hire someone with them, but at the end of the day I have met many great developers and talented people in other fields with hundreds of tattoos, brightly coloured hair and piercings.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.