Bing Webmaster Tools will now be showing integrated data from Yahoo within certain areas and reports. Given the combined effort the Search Alliance represents, it makes sense to showcase relevant data from both engines within a webmaster account. Most areas and data within the accounts will not be affected. The short list of areas you will notice changes in are as follows:
On the Traffic Tab: Traffic summary report and Page Traffic reports will be impacted as follows:
Impressions – will go up based on combined data numbers
Clicks – will go up based on combined data numbers
Click Through Rates (CTR) as appropriate from above (change only due to the mathematics involved in the first two items)
Impressions data will rise because we will now be showing you combined impressions for your listings across both search engines. 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 changes affect the numbers shown only. 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.
At this time the data will be combined, not selectable. The data will also update in any market where Bing is powering Yahoo search.
The data integraton began on August 12th. It took roughly four days for all of the data to populate across accounts to the full extent. For the month of August, accounts will note the changes in data numbers between the 12th and the 16th. September will be the first full month of combined data.
Source: Bing Webmasters Center Blog