Big ecommerce websites that sell and frequently update new products online are more susceptible to Google indexing problems. A combination of different factors can contribute to slow website indexing, most of which can be controlled by the webmaster.
http://www.seochat.com/c/a/Google-Optimization-Help/Improve-Google-Indexing-on-Your-Ecommerce-Website/
Traditional SEO has centered around moving one web site higher in the search results. The latest forms of SEO such as SEO Monopoly center on moving multiple sites higher in the search results.
