The Yahoo Search Blog recently announced the launch of BOSS -- an "open platform that offers programmatic access to the entire Yahoo! Search index via an API." BOSS currently lets you re-rank and blend results, gives you flexibility on presentation, includes a mashup framework, has web/news/image search, and entitles you to unlimited queries.
The BOSS platform has had a lot of Techmeme buzz, but forum members doubt its capabilities. As WebmasterWorld members claim, search is not one of Yahoo's stronger suits. Yahoo has much better content.
However, not all are quick to discount BOSS. Brett Tabke, WebmasterWorld administrator, believes that this is one of the "most interesting development in search in a long time" and is willing to give it a try. Giving you control as boss (no pun intended) may be a really good direction for Yahoo -- and for you as a searcher.