Ron Amadeo, for Ars Technica:
The idea is to offer a better way to get media and other search results into your conversation. If you wanted to show a friend a trailer on YouTube, the normal work flow would involve leaving the app, opening search, typing your query, copying the result, going back to the messaging app, and pasting the link. Gboard lets you do all that without leaving the current app while saving you a few of those steps.
General creepiness of having Google track your keyboard taps aside, this is a great idea. Why can’t Apple do something similar with their Siri button? Sigh.