I believe the hoo-ha over pages in the supplementals is based on an outdated concept. I have several sites which now have a larger proportion of pages in the SI than before; these are not duplicate content pages, but pages with similar listings, such as real estate listing detail pages and vacation rental listings. It makes sense to me that these pages are in the supplementals, as they generally have only one link to them from a menu page.
The greater proportion of pages in the SI has not affect my sites SERPs or traffic. I wouldn't expect those pages to come up for the more competitive terms, but some rank well for longer tailed terms, just as they did before.
I know this is 'old news', but since many webmasters still seem overly alarmed by pages in the SI, I think Matt Cutt's post last January bears excerpting (bold are my addition):
As a reminder, supplemental results aren’t something to be afraid of; I’ve got pages from my site in the supplemental results, for example. A complete software rewrite of the infrastructure for supplemental results launched in Summer o’ 2005, and the supplemental results continue to get fresher. Having urls in the supplemental results doesn’t mean that you have some sort of penalty at all; the main determinant of whether a url is in our main web index or in the supplemental index is PageRank. If you used to have pages in our main web index and now they’re in the supplemental results, a good hypothesis is that we might not be counting links to your pages with the same weight as we have in the past. The approach I’d recommend in that case is to use solid white-hat SEO to get high-quality links (e.g. editorially given by other sites on the basis of merit).That said, I am not suggesting that having pages in the SI is a good thing, just that it is not the death knell that it was once believed to be. Here are some ways to get pages out of the SIs:
I think going forward, you’ll continue to see the supplemental results get even fresher, and website owners may see more traffic from their supplemental results pages. To check out the current freshness of the supplemental results, I grabbed 20 supplemental pages from my site and checked out their crawl date using the “cache:” command and looking in the cached page header. The oldest supplemental results page that I saw was from September 7th, 2006 (and I only saw 2-3 pages from September; most were from December or November). The most recent of the 20 pages was from January 7, 2007, which shows that supplemental results can be quite fresh at this point.
Please feel free to add any tips for getting out of the supplementals ... or to disagree.
- ensure the content is unique
- add fresh content
- make sure all pages have unique title and meta description tags;
- obtain high quality, trusted links;
- restructure or create more internal links;
- link out to relevant authority sites;
- check for broken links;
- make sure you have no canonical issues.