Back when the Microsoft and Yahoo search and advertising deal was announced, people (particularly developers) were left wondering what would become of such Yahoo projects as Searchmonkey and BOSS. These things let developers build upon Yahoo's search technology.
Microsoft did imply it would be open to keeping them around, but not much has been revealed about the plans. While this isn't exactly clarity, Yahoo has addressed the future of BOSS to a mild extent. In a post on Yahoo Groups, Ashim Chhabra of the Yahoo Search BOSS Team writes:
Under this agreement, Yahoo! is permitted to continue offering the BOSS web service, with search results that would integrate Yahoo! services and content with algorithmic results provided by Microsoft. As always, our intention is to provide a BOSS offering as long as it makes business and economic sense to do so. We are still examining what the BOSS offering will consist of, with some services powered by Microsoft, unique content that Yahoo! currently provides, and the potential for additional Yahoo! content in the future.
Prior to the announcement of the Yahoo!-Microsoft search agreement, we'd already shared our intention to explore a fee-based structure for BOSS. We continue to explore an appropriate fee structure or other revenue model as we work through the future of BOSS.
Yahoo has said that it will uphold the front-end part of its search engine, but the back-end would generally be handled by Microsoft's Bing search engine. Last year, Microsoft acknowledged that it liked what Yahoo was doing with Searchmonkey and BOSS, so it is quite possible these things will remain.
The Microsoft Yahoo deal is not necessarily going to be a permanent relationship anyway. That is if it even gets approved. The deal still faces regulatory approval.