Bing has just implemented a new feature in which users can now interact with their searches in a whole new way, allowing them to participate in conversations with the Microsoft search engine. The feature retains the context of previous searches, and by doing so, is able to understand searches that relate to the original topic. For example, if a Bing user searches information about who the current President of the United States is, Bing will provide Barack Obama as the answer. If a user continues to ask follow-on questions, such as who he is married to or how tall he is, Bing will recognize that President Obama is the subject based on the prior search and will continue providing relevant information on him.
Source: Bing Blog