It seems that this prompt appears with every search, so it’s not limited to specific topics. When clicked, a conversation box will appear, which is similar to the box that you see when sharing something that you’ve +1’d. Text related to the topic is provided, but users can add more, which will help give context to the question.
Additionally users can choose which Circles to share the question with. For example, if an individual has a question about Italy, he or she can direct the question to friends that have been there. Brands will also benefit as consumers can ask questions regarding a product or service directly from search results.
This new feature is a subtle way to initiate conversations on Google+. It feels less intrusive than Search plus Your World, and just might be enough to encourage more sign-ups for the social network.