If you were hankering for some tacos, for example, you could just tweet "🌮 @google" and wait for a reply. The company says it supports 200 emojis so far, along with some "easter eggs," according to Mashable. It's not exactly useful -- it's much easier to just type actual letters into Google -- but it's a fun feature that could distract your friends for a few minutes. It could also be a way for Google to get a sense of what emoji people actually use for whenever they implement emoji support in its search apps.
The feature isn't completely foolproof. It won't be too long before you run into simple emoji that Google should really get the hang of. For example, my expression upon reading about this news for the first time: