I only have a generalized understanding of what "SEO" and why it is important. I have a couple of sites using the BANS software. When BANS places the 20 or so auction listings on each page of my website, do the search engines see those on my site. For example, it is not uncommon for the ebay listing in my niche to have a pretty detailed description. I get up to a hundred of those through the RSS feed. Do the search engines see this?
most likely not - as those auctions come and go too quickly to "stick" on search engines. However they are noticing your page, your URL and any static text/links/images you have on the page.
with bans search engines do certainly "see" and register the content that your rss feed brings. i have a few bans sites and notice that once you receive some organic search clicks you will see in your stats some of the keywords that brought people to your site and they won't be keywords that you have placed on your site they will be from the feeds. although all traffic is potentially good traffic this can have a small drawback in that if google visits your site say on 25/10/07 and then someone searches for item xyz on 1/12/07 google will take them there but the item is gone. as the rss feed is constantly changing. good luck
Another useful aspect of BANS is that you can customize each page that lists separate items in your store with meta descriptions and meta keywords through the "edit pages" in the admin section. This is also good for search engine notice.