While the image is owned by the copyright holder, most vendors release those copyrights when they push those images through news services like PRN Newswire for full-release in editorial content, such as magazines, websites, reviews, etc. and make them available for public use, similar to public domain.
There is no violation, when the advertisers releases those images through PRN Newswire (or a similar news/PR
agency) the same ones they use on their website, when the image is used to promote their products.
Most advertisers will give you an arm and a leg to promote their products. On the ones I've posted so far, I personally spoke to the company marketing reps at PMA--there response, go for it! The key is for the initial posting with their released text, not for the review one would post that would be opinionated. (these are product shots without models that they, the manufactures, release themselves for editorial use, including reviews)
In other words, for the initial product posting, as long as it's not altered or skewed from they way they release it through PRN or their own website, it can be used--but not in the follow on reviews. In fact, most vendor sites have areas to download images, releases, etc., on thier products. Obviously, you cannot alter the image, nor superimpose it with say a "model" or something that defames the product.
On a side note, ever notice why almost every camera store uses the same images and marketing text? Or why photo magazines use the same product images? These come straight from the vendor.
Hope that helps, thanks, rg sends! (This image I shot and was originally posted on Newtek.com's web site with the idea anyone could download and use it for promotion of their product, hence no copyright notice.)