Market research & consulting: perception and acdemic career perspectives
I can't speak for the IS field, but I think that there's a strong chance that your time in industry would be considered as a break from doing research relevant to academia. Unless you are regularly publishing papers in the relevant journals or conferences, your time working outside of the academy will be perceived as time idle. 

Now, that being said, market research is a field frequently included in Business Schools. I don't know where your IS degree is from (Communications? Business? somewhere else), but I think that Business Schools are much more likely than other departments to value time spent in industry when hiring professors. So, there are probably different standards for evaluating your output during your time in industry. Published reports about the state of a market might be more acceptable as a valued contribution to the literature, and therefore less likely to paint you as having been out of touch with the academic literature.