Introduction
I am by no means an authority on SEO optimization. I just learned .Net a year ago and Solunar.com is my first online storefront experience.
What I do know is my experiences in taking advantage of the SiteMap feature included in AC7.
The purpose of this document is to detail my experiences, the steps taken and the bumps in the road along the way.

What is SiteMap?
The three largest search engines came together several years ago and agreed on a standard for bulk site URL submission. You can easily submit a single domain name to any search engine, but getting all 12,000 products in your store submitted as SEO-friendly URLs is a different story.

This standard resulted in the definition of what is known today as the "Sitemap.xml" file format. The format specifies the fields necessary to submit any number of URLS to the search engine for indexing.

Why should I care?
Well, you can't really grow a business if nobody knows it's there. Getting into search engines is the single most important step with an online store. Plus you'd like your business growth to be more than one more order this week than last week.
Using a sitemap file also reduces webmaster effort to maintain search engine presence. And it reduces unnecessary spider/crawler traffic on your site.
Whatever the reason, the benefit of getting into the search engines quickly and accurately is significant. Sales pick up quicker, loss-to-profit timetables accelerate and your customer base grows sooner and at a faster pace.

Where to Start
First you need your products set up in your store. It's not going to do alot of good to tell everyone you're open for business if your shelves are empty. Get your images, descriptions and prices all the way you want before proceeding any further.
Once you feel you're ready, login into your site Admin and click the Website, XML Site Map option.

Don't change anything. Let's not get fancy at all right now. Especially don't change the sitemap.xml file name. That's part of the standard and if you mess with it, you might not be successful in getting your sitemap file read by the search engine provider.
At the bottom of the page, set the dropdown menu to "Create Sitemap" and click the blue arrow. Don't click save settings, that's not going to do the task – that only saves the screen changes I just got done telling you not to make.

When it's done, you'll get a confirmation at the top. The sitemap.xml file is created in the root of your site. Check it out if you want, but don't change it.

Autodiscovery
In the Spring of 2007, the 3 big players (and a few smaller ones) in the search engine provider industry enhanced the sitemap standard by implementing a uniform way to upload your file. it's really incredibly simple: Just send them a URL with a parameter for the URL to your sitemap file.

For example, to tell Ask.com to come get your sitemap file and process it, just enter this URL in your browser:

Code:
http://submissions.ask.com/ping?sitemap=http://www.example.com/sitemap.xml

Or Google.com

Code:
www.google.com/webmasters/tools/ping?sitemap=http://www.example.com/sitemap.xml

Other major search engines should support this same format but check if you aren't sure it worked. You should receive a confirmation page from the search provider indicating the request was received.

How Often?
Well, that's the million dollar question. Nobody really knows for sure. I do mine about once a month, or whenever the mood hits me. I doubt doing it every day is going to help your cause, so you should probably limit it to when you have truly meaniful changes to be uploaded.

Spider autodiscovery
You can also tell any spiders that crawl your site to read your sitemap.xml file. Just add this line to your robots.txt file in the root of your store:

Code:
Sitemap: http://www.example.com/sitemap.xml

Advanced stuff with Google
Google.com has some amazing site tools for webmasters. Just go to Google.com and search for "Google Webmaster Tools". Sign up for it. It's free, it's awesome and you really should check it out. It's worth it, trust me.
One important part of the webmaster tools is "Google Feed" which lists all of your store products into the Google Product Search.
And yes, this just happens to also be where you'll upload the file produced by the AC7 Marketing, Feeds, Google Base Feed menu option. And it's still free because it's beta. But don't let the word "beta" scare you away, I am getting ALOT of orders from Google Products Search.

More Information
There are quite a few great articles on sitemap implementation. Try http://www.sitemap.orgor search any search engine provider for "sitemap information".

Conclusion
Making yourself known to the internet is the most difficult and most rewarding step in running an online store. AC7 has made this much easier for the site admin by supporting the SiteMap standard. Combined with other forms of online presence development, your site awareness is sure to grow as will your business.