The fastest rising Google query was Chatroulette, the name of "a Russian based website that pairs random strangers from around the world together for webcam-based conversations". It was followed by iPad, Justin Bieber, Nicki Minaj, Friv (a popular online gaming site), Myxer (a site that offers ringtones, wallpapers and apps for mobile devices), Katy Perry, Twitter, Gamezer (multiplayer games) and Facebook. As you can see, the fastest rising queries were related to social networks, mobile devices, games and music.
This graph only measures relative growth, not search volume:
It's interesting to see that there's only one Android phone in the list of top 10 fastest rising queries in consumer electronics: HTC Evo 4G. Apple's iPad and iPhone 4 are the most popular consumer electronics devices, according to Google's search data. iPad is also the fastest rising query in the US.
If you go to Google Insights for Search, you'll find different results. Most of the queries from the top 10 fastest rising searches are related to Facebook.
Google even uploaded a creative video that shows the most important events from 2010:
There's also a list of the most influential YouTube videos of the year.