The update is rolling out now and should be available on most Tap devices in the coming weeks. To see if you have it, open the Alexa app, go to Settings, select your Tap and slide Hands-free mode on.
After that, you should be able to command your Tap by simply saying "Alexa" like you would on an Echo or Echo Dot (the feature didn't appear to be available quite yet on my unit).
As its name suggests, the Amazon Tap is a wireless Bluetooth speaker that formerly required you to tap a button to ask Alexa about the weather, order some food or perform any other command. In our initial review, this limitation proved frustrating, and we found that the Tap's battery life and sound quality to be a bit behind some of the better Bluetooth speakers on the market.
Still, the $129 Tap is significantly cheaper than the $179 Echo, and now offers the same hands-free Alexa experience (the $49 Echo Dot doesn't play music well on its own). Considering that it's the only Alexa device designed to work both at home and on-the-go, this new update makes it a much more appealing buy.