Yahoo announced this week it is beginning a crucial part of its transition to providing Bing search results from its websites -- but whether advertisers will actually make the move this year is still in question.

Users will be able to tell when the process has kicked in because there will be a Microsoft (NASDAQ: MSFT) "Powered by Bing" logo at the bottom of Yahoo's (NASDAQ: YHOO) search results screen.

At the same time, the two companies are ready to begin moving a limited set of Yahoo advertising accounts to Microsoft's adCenter.

"Later this week, we will begin the work of transitioning the back-end technology for Yahoo Search over to the Bing platform," said a post Tuesday on the Yahoo Search Marketing Blog.

"This is an important step toward our goal of improving the overall relevance of Yahoo organic search results and attracting a larger audience to Yahoo Search, to ultimately put your ads in front of more potential customers," the post continued.

The start of the move to the Bing infrastructure also comes with news that testing has begun on transitioning paid search accounts from Yahoo's Search Marketing system to Microsoft's adCenter -- something of critical importance for search engine optimization consultants and ecommerce advertisers.

"Soon, you'll be able to access a transition portal from within your Yahoo Search Marketing account [which] will walk you through the simple step-by-step process of creating a Microsoft Advertising adCenter account and importing your campaigns, or linking an existing adCenter account that you may already have," the blog post said.

The current testing is being done using a limited number of advertiser accounts in order to assure a smooth transition. When the transition portal is live, Yahoo said it will notify customers via e-mail.

The Yahoo blog entry, however, made a point of emphasizing that nothing is set in stone yet regarding when the actual transition will take place. The current target is still to have the transition completed before the 2010 holiday shopping season, but Yahoo repeated its earlier statement that if problems crop up, the transition could be postpone until early in 2011.

Last month, Yahoo announced it had started testing delivery of search results to Yahoo sites using the Bing technology. The plan at that time was, and continues to be, to transition the U.S. and Canada first.

Microsoft and Yahoo appear to be in agreement on the latest developments.

"In the upcoming days we will begin the organic (algorithmic) transition, which means that soon Bing will begin to power the English language organic search results on Yahoo Search in the U.S. and Canada," said a post, also on Tuesday, to Microsoft's adCenter Blog, by media specialist Tina Kelleher.

"Once this organic transition is complete, Bing will power 5.2 billion monthly searches ... that's 31.6 percent of the search market share in the U.S ... and 8.6 percent share in Canada," Kelleher's post added.

Stuart J. Johnston is a contributing writer at InternetNews.com, the news service of Internet.com, the network for technology professionals. Follow him on Twitter @stuartj1000.