The Media Post blog has covered the story about the ongoing integration between Yahoo! and Microsoft search and in particular, the impact on their respective paid search (PPC) services. This follows blog posts by both companies, including answers to questions raised on the Yahoo! blog.

Microsoft and Yahoo have recognised the concerns expressed by existing advertisers of their two services as progress is being made towards moving all customers to Microsoft's ad platform adCenter. Both services currently offer different features and although the general consensus is that the adCenter platform is more user-friendly, the changes could take longer than expected.

The article outlines the type of issues being discussed, such as style issues regarding how singular and plural words that YSM sees as one word, but Bing does not. Also, whether liquor advertising keywords - which are allowed on Yahoo - will work on MSN, which does not allow liquor keywords like scotch. One key question is also whether advertisers will have the option in Microsoft adCenter to choose which search engine to run campaigns on - either Yahoo, Bing or both - although the current response seems to be negative.

These minute, but important, details could hold up any project this size. The two companies announced an alliance back in February, that would provide advertisers with the potential to reach more consumers through one account. Yahoo would sell the search ads through the adCenter system, but not the display ads for both companies.

The plan has been to transition US and Canadian customers to adCenter before the start of the holiday 2010 search period, but in a recent blog post to advertisers this is now expected to take longer - probably into the early part of 2011.