TechCrunch reports that Yahoo! is experimenting with integrating del.icio.us bookmark data into regular search results.

After the regular search listing Yahoo! will add a line saying something like “X people bookmarked this page under [these categories]”.

Yahoo! bought this very popular online bookmark service in 2005.

del.icio.us lets you add bookmarks (or favorite web pages) to your own account and add comments and tags. You can then go back to del.icio.us to retrieve your bookmarks and search the favorites of others.

There are several reasons for why Yahoo! may be contemplating such a move:

• The line of text provides added value for the searcher. It says something about the quality of the relevant page.
• The fact that categories are included helps the searcher judge the relevancy of the listing.
• Yahoo! may use the del.icio.us entry to recruit more users of the bookmark service.

The last bullet point is important, because Yahoo! may use del.icio.us data not only to augment search engine listings, but to generate them. In other words: Yahoo! may add another factor to its search algorithm, giving much bookmarked sites a boost in search engine rankings.

Thriving bookmark services are relatively hard to spam. A proper bookmark can definitely be counted as a vote of confidence in that page.

Whether Yahoo! already has integrated bookmark data in its algorithm is unknown.

Michael Arrington over at TechCrunch adds another relevant point: You can use the del.icio.us search engine to search for sites, and given that the del.icio.us database only includes pages that someone has found valuable, the search results are quite good. Try it out for yourself!

Google is at a disadvantage in this area. Google has its own bookmark service, but it is close to invisible, and cannot compete with the likes of del.icio.us.

See also Top 5 Social Bookmarking Services
. Since we wrote that article Yahoo! has refined its own branded bookmark service: Yahoo! Bookmarks. Yes, it has two of them, and Yahoo! Bookmarks is now one of our favorites!

We have not been able to replicate Techcrunch’s results from Norway, which proves that this is a test.