An Introduction to Google Webmaster Tools
It can take anywhere between a few weeks and a few months before search engines, such as Google, index your store and begin to show it in their results pages. To help speed up this process, you may want to consider signing up for Google Webmaster Tools and submitting your Sitemap to them. This will provide them with an up-to-date list of all pages on your store. While this is not guaranteed to speed up the indexing process, it should at least ensure that Google has a clear map of your entire store.
For more information and to sign up, please see: http://www.google.com/webmasters/tools/