A fascinating remark made by the Vice President of AskJeeves, Jim Lanzone, on the subject of the recent nofollow tag that is being adopted by Google, Yahoo!, MSN and many of the major blogging services gives us great insight into the world of search. Here is an excerpt:

On the other hand, when it comes to our particular engine, we didn't need to make a snap decision here. The nofollow idea is more urgent for Google (and those with similar approaches) than for Ask because they use global popularity (PageRank) while we use the local popularity approach pioneered by Teoma. I'm sure we'll add support for the new tag at some point in the near future if it makes sense.

This revealing quote is not a revelation, but it should be something that SEOs think about as they optimize for search engines. Sites like Yahoo!, MSN & Google are unlikely to be purely focused on global authority and local authority should be a large part of any SEOs optimization tactics.

What is local authority? It's the popularity (read: link popularity) of a particular site among sites in their topic community. So, a link from Wikipedia or Yahoo!'s directory, despite being on an on-topic page, will not count towards local authority, while a link (even a reciprocal link) from a website in your own industry that's geared towards a related topic or the same topic as your own website, is a boost in local authority.

SEOs should concentrate on making sure that their local authority status is in line with their global authority status. A disparate number of links from non on-topic sites might be a good clue to a savvy search engine that your link-building efforts are 'manipulating' the SERPs. How do you check your local authority? Try Teoma or AskJeeves. Their link popularity is almost entirely concentrated on local authority.