To be honest, most of my candidates at my current company are just beginning their career, so I can't say this comes up much though.

I have been in HR/recruiting for about 13 years, though, and the answer has changed a lot. There used to be a big stigma attached to being a job hopper, but that has lessened greatly over the years. I read a Bureau of Labor statistic that the average 32 year old has had nine jobs since graduating from high school.

I do think the age of the person interviewing you matters, and I also think the region matters. Here in Milwaukee, people frown more on jobhoppers, but when I lived on the east and west coasts, it was no big deal.

I am in my mid-30s and have switched jobs every 3 years or so...it hasn't slowed me down.