Get Your E-Store Reviewed on Facebook
Considering the price (free) it certainly isn't a bad idea to put one up. Especially since any of your fans can set up a page on your behalf without anyone knowing it wasn't you, so it's a good idea to be the first out of the gate so there's no confusion and you can control your introductory message and the way your Page functions yourself. Other users of Facebook could still set up unauthorized Pages, but at least the early fans won't be usurped by the unofficial Page.
Get Reviewed on Facebook
Unlike Facebook Groups and Sponsored Groups, Facebook Pages are like people -- they can add applications. One application that is useful for online retailers and other businesses is Reviews. Reviews can only be added to Pages, not individual profiles, so you won't find it in your regular applications search, but you can view the application page through the link.
Zappos and NewEgg are two e-tailers who have won the hearts of loyal customers through their commitment to customer service, and it shows. Both retailers have earned shining reviews of their businesses on their own Facebook Pages, which *may* appear in search engine results. (NewEgg's Fan Page does not appear in search engines because it hasn't been indexed as of today. Perhaps the link from Get Elastic will help it get crawled.)
Attracting the Fans
I haven't seen this used yet, but a great way to encourage people to join your Facebook Page is to include a call-out somewhere in your email campaigns, post-purchase thank you pages and even right on your website or blog. Of course, you can also experiment with Facebook's Social Ads to get the ball rolling.
Once you have fans, it's like having an additional opt-in list that you can send Page updates to. Similar to emails through Facebook groups, your fans will be notified of new events or other updates through their Notifications feed. Just remember signal vs. noise - you'll lose Fans if you send out too many updates with little value.
Are you brave enough to add customer reviews to your Facebook Page?