Bing announced that it is now integrating Yahoo traffic data into Bing Webmaster Tools. It’s a little surprising that they’ve waited this long to do so, as the Search Alliance between Bing and Yahoo has been in place since last fall, but better late than never.

“The changes affect the numbers shown only,” says Bing’s Duane Forrester. “No actual rankings will be affected by the combining of data within Bing Webmaster Tools. As a visual reminder that data is now combined, you will see both the Bing and Yahoo logos directly above the graphs shown on these pages.”

Most areas and data within webmaster accounts, will not be affected, he says. In the Traffic Summary and Page Traffic reports, you should see an increase in impressions, clicks, and hopefully clickthrough rate, as a result of the combined data numbers.

“Impressions data will rise because we will now be showing you combined impressions for your listings across both search engines,” says Forrester. “For each query term in the list within the report, your impressions represent the combined number of times your result showed, based on queries initiated by searchers at both Bing and Yahoo.  Clicks data will follow the same pattern.  CTR data is a factor of the first two items, and will rise or fall based on searcher click activity at each search engine.”

The data will only be combined, and not selectable, at least at first. It will be updated in all markets where Bing is powering Yahoo Search.

The actual data integration starts from August 12, and Bing says it took about four days from then for the data to completely populate across accounts. In other words, you can look forward to September as the first complete month for the combined data.