The magic starts here -> http://miku-39.jp/
The site has been updated to allow you to play a special video that lets you connect by sharing your location, twitter account, or by connecting with your mobile device. Connecting with all three would be recommended, as that’s when all the features will be available (it’s an interactive video!). Interesting things will appear based on how you choose to connect, and I’m unsure what the differences are between them (I’m currently lacking a high end mobile device).
If you remember from a short while ago, you were able to send a birthday message to Miku using a blank letter on the site. You’ll be seeing a lot of those messages pop up in this video.
Go check out the website, connect using one or more of the options, and enjoy! If you connect using a PC, using the most up to date versions of Firefox or Chrome is recommended, as it’s coded in HTML5.