By far the most important factor in where you rank in a search engine for particular keywords relies heavily on the content of a page: in short, what words you have on the screen. This piece in NMA highlights the value of incoporating (& publishing) news content on your shopping site. We agree.

There are many benefits to news content: not only will news content enhance the look and feel of your website, giving users something worthwhile to read, it also increases search engine spidering, branding opportunities (through syndication tools such as RSS or Google News) and by increasing the number of indexable, keyword relevant pages available on your website, will increase visitor numbers, too. News content will also get you inbound links from blogs, websites and twitter if your content is good enough, too.
"Major changes in how we use the web are also in favour of producing daily news content online, all you have to do is visit Google right now to see. The recent new interface on Google results is opening up previously hidden (or at least hard to find) sections of the web to new users. By allowing you to search by time, day and weeks, as well as making it easier to search specifically on things like blogs, social media, video and, of course, news, Google is inviting websites to update their content more regularly and offer users something new."