Google recently announced  a feature enhancement in the Keyword Planner in Adwords, and it looks like it has finally rolled out to most accounts.

The Keyword Planner will now allow advertisers to compare impression share with competitor domains and the top five market leaders.

The competitor domains impression share is calculated based on the last 30 days and is associated with the generated keyword ideas and a product category the advertiser should select from the drop-down.

The view with market leaders will show top five domains, then an average impressions share percentage amongst the market leaders for comparison.

This information can be helpful to identify the top competitors, their impression share ranks and how it compares to others. By changing the keywords or category, the competitive information may change as well.

It would be helpful to try combining impression share, competition, and average monthly searches to find pockets of opportunity for new keywords.  It also is a great tool for doing competitive analysis on competitors you know about, as well as some you might not be as familiar with due to geotargeting usage by those competitors.

The enhancement seems to be available to most AdWords accounts now.