This piece of kit is SNAZZY! It's been used a lot by up and coming 'Little Boots', who you can see below using it to perform a Hot Chip cover, although you should take a look at the second video to see more of what it can do. It was invented by Toshio Iwai who, surprisingly, is a Japanese bloke who is into electronic music. It is one of the most impressive digital musical instruments I have ever seen, although it costs a steep £750 to get hold of one in the UK.
*UPDATE* Thanks to Sam for showing me ToneMatrix, which is a simplified version of Tenori-On which you can play about with online! Make sure you have the latest flash player installed.
In other news, despite going absolutely INSANE from revision, I have been enjoying Passion Pit who a have a new album out on the 19th called Manners...in the meantime, here is their video for the song 'SleepyHead'.