As the web grows and develops, so to does the complexity of search, particularly Google. One aspect of search rankings that may take effect in the future is the social aspect of websites. User generated content has been term used in the past, its search engine optimization value into the future may be important.
If you have an ecommerce site then you should be encouraging your customers to write mini product or service reviews, or at the very least, leave comments. If social and user generated content does get included in the search ranking algorithms, your site will have a head start. It can make good SEO sense to incorporate it now for other reasons.
Your keyword lists should include your products. If they do, every comment or product review will include the product name. If the review title is used as anchor text to link to the product itself, you will have a well optimized internal link. If you prefer your product reviews to be on the product page, then the review will add to the number of keywords on that page. Either way, your search engine optimization efforts are being given a boost by your customer.
Product and service reviews can also be a perfect way to build a reputation. Even if the occasional review is negative, provided you have included the option to respond, you can provide solutions (not excuses) for the negative comment.
Product reviews that have been generated by your customers can be good for both your online strategies, your reputation, and of course as free on page independent marketing tools.