Amazon Echo update lets you control iTunes, Pandora, and Spotify with your voice
Although the Echo could previously play music from the aforementioned apps and services, ZDNet says, it couldn't control playback--you had to actually control playback yourself through your phone. So last decade. It still won't start playback, though--you have to initiate that.
In other words, you shouldn't have to do anything to get the update: ZDNet's James Kendrick says his Echo already has the update, so it appears as though Amazon is automatically pushing the update out to users. If you haven't received the update yet, you should get it soon.
Why this matters: The Amazon Echo is best describes as "Siri for your home," and this latest update helps it become a more complete virtual assistant. Although you need to request an invitation to purchase the $199 device ($99 for Prime members), this approach gives Amazon an opportunity to test features, add functionality, and get a feel for what the device can do before it decides to release the Echo to a wider audience.