Search engines are said to use clickstream data to a certain degree as a ranking factor. Adjusting a meta description can affect your click-through rate. I would guess that a meta description has the potential to indirectly impact your search rankings. I think the impact is probably not noticable on one or two pages, but perhaps scaled across a product catalog maybe.
Again just a guess based off of what I've read. I'd welcome anyone to add to or counter it.