I know what a "sneak peek" is...that's the early first look (or, "peek") at something not yet officially released for public consumption. One surreptitiously--or at least, in a manner that is made to seem surreptitiously--views (or, "peeks") the subject in question, and has therefore been given a "sneak peek" at the subject.
And yet I keep seeing professional magazines and newspapers going on about giving their readers a "sneak peak," at something or other, which to me sounds like the top of a mountain that suddenly appeared out of the cloud cover and at which you screamed in terror right before your tiny plane crashed into it and exploded.
Or, if one is being less tangible, it could refer to a career or other business-related peak, albeit one that occurred without your knowledge or forethought. Suddenly, your struggling ska-core band breaks through with a catchy single that you didn't think even belonged on your self-titled EP. Suddenly the product your small company produces gets featured in an episode of Grey's Anatomy and everybody decides they want the hell out of it. But little do you know, of course, that your band is a one-hit wonder, and that the fad for your product will die out completely in a few months, taking with it what was your profit margin.
That must be what they are referring to, surely. It surely couldn't be a blatant misspelling that has infiltrated the lexicon to the point that even people who should know better are disseminating it in their carefully edited publications.