I'm playing around with the "Featured Products" feature in the tools at AvantLink. I'm sure other technologies have something similar or it could easily be home scripted with PHP.

Here is the way it works. When you open up a page with links to different category groups there will be three random products displayed below under "Featured Products". These each have links to Product Detail pages.

When you do a sitemap some of the pages listed will not be available during crawl by a search spider. It will be like they are there but not linked in the site.

I'm wondering if this having links in the sitemap that are not available during the normal spider crawl will cause any problems. The category page will look like it's content changes a lot and I have no idea whether that's good or bad.