When do sitemaps become doorway pages?
Nothing wrong with them from what I can tell. The problem is with the general vagueness of the term "doorway pages" that's come about over the years, and the checkered history of how these pages have been used.
Sitemaps apart... the original idea of a doorway page was a well-focussed optimized page that linked into a site and attracted search.
I'm not clear whether, with the early doorways, the site didn't link back to the doorways, but ultimately that's where the idea was taken... so someone browsing your site couldn't accidentally navigate to such a page if it didn't fit well into the overall scheme of the site.
Questions then came up about how many doorways a specific search engine might allow. This was pre Google and pre PageRank, but there may have already been some linking considerations in operation that we were unaware of.
Variations on doorways came to include machine-generated pages seeded with keywords, and eventually cloaked doorways. Eventually, some years back, AltaVista came down hard on WebPosition Gold generated doorways, causing all sorts of turmoil, and throwing the name "doorway" page into general disrepute.
Then along came Google with PageRank. Even when they're not cloaked and not machine generated, the one-way pages don't do well on Google. Such one-way pages have been called "orphan" pages, and some commentators believe that these orphans are penalized by Google simply because they're perceived as doorways.
I think that orphan pages don't do well because they don't have any PageRank, something which the algo probably anticipated. Efforts to get PageRank to these pages came to include hidden links, and, when hidden links became widespread, Google began to penalize for them.
I've always considered any page on a site to be a potential doorway page, in the sense that it's designed to attract traffic. Over the years there was a perception that the better integrated into the site the doorway was, the less likely it was to cause trouble and the better it did.
As you've observed, a page that's well integrated into the rest of the site gets good PageRank from the site. Such pages are great candidates for optimization, and I don't think there's anything wrong with that.
Site maps are excellent candidates for optimization anyway... I like to keep enough text between each link that they feel like a mini-directory. An ODP page, or a Yahoo page without the ads, is a good model.
GRML Blog
GRML Blog
GRML Blog
GRML Blog
GRML Blog
GRML Blog
GRML Blog
GRML Blog
GRML Blog
GRML Blog
GRML Blog
GRML Blog