Google just announced a new feature that allows you to specify the canonical URL for a page.  Yahoo also supports this tag, and MSN intends to as well.

Many websites can show the same content under different URLs.  Often this is just how many ecommerce and content management systems work — they generate URLs with various tags, parameters, path names, etc as a way to allow the back end technology to keep track of the page being displayed, as well as the context in which the page was generated (e.g., the catalog category for an ecommerce site, where the product being displayed may be shown in several categories).

For example, the following all might be the same page:

• www.mysite.com/icecream/vanilla.html
• www.mysite.com/desserts/vanilla-icecream.html
• www.mysite.com/products.php?type=vanilla&category=icecream
• www.mysite.com/products.php?type=vanilla&category=desserts

You can also get variations based on inconsistent capitalization:

• www.mysite.com/IceCream/Vanilla.html
• www.mysite.com/icecream/vanilla.html

The problem with showing the same content under different URLs is that it can damage your SEO rankings.  (more…)

Online Ad Revenue YoY (via techcrunch)

Google, Yahoo, Microsoft and AOL have all finished reporting their earnings for Q4 of 2008. The result? Growth! After seeing their revenue growth decline every quarter in 2008, their ad revenues actually started to pick up in Q4 by 3 percent. Together they showed a 8 percent growth year over year. In Q4 of 2007, the search engines showed a 12.7 percent growth year over year. By Q3, growth rates was only 0.6 percent year over year.
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