First time i saw it, i was is this flash or silverlight or plain good old javascript.
seems google is coming up with new innovative concepts

Users visitng the search engine's home page this morning were greeted with a flurry of spheres.
The balls can be dispersed around the page by moving the mouse, but gradually form into the Google logo if left alone.

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Google has released no clues for the the reasoning behind the doodle. Usually such designs are created to mark and event or an anniversary.
A Google spokeswoman was unavailable for comment on Tuesday.
The mysterious Google Doodle is the third interactive design released by the tech giant.
Last weekend Google marked the 25th anniversary of the discovery of the "buckyball", a spherical dome of exotic molecules of carbon, with a special moving design.
The animated logo replaced the logo's middle O letter with an orange ball. It then formed into the "buckyball", which is a form of carbon composed of 60 atoms.
By scrolling their mouse across the logo, users could twist and turn the ball, which has replaced the search engine's usual logo on its home page.
The logo was rolled out across the world on Saturday to celebrate the quarter of a century since its discovery.
The new interactive doodles follow one produced in May to celebrate the 30th birthday of Pac-Man.
That design, which went public on Friday, May 21, 2010, was the first doodle to be fully interactive. The Pac-Man character could be moved by using the arrow keys on the user's keyboard.
Google Doodles have become newsworthy in their own right after the technology firm started using the customised versions of its logo to mark what it considered significant occasions.
The first of them was used in August 1998 when Sergey Brin and Larry Page, the firm's founders, designed one for the Burning Man Festival.
In October 1999, it produced a Halloween doodle: the first after the firm switched to a new logo.
The first "Christmas card" doodle was presented in 1999, on Christmas Day, featuring a snowman and flakes drifting onto the name.
Mother's and Father's Day doodles appeared in May and June 2000 respectively before the firm started noting more esoteric and, let's face it, interesting occasions.
On October 7, 2009, it did "Google" as a bar code to recognise the anniversary of its invention in 1948 by Bernard Silver, which some saw as a significant shift away from human language and towards machine language.
On Saturday, June 5, 2010, a hologram replaced the logo to honour Dennis Gabor, the inventor of holograms.
Most recently the firm marked the 71st anniversary of the Judy Garland film The Wizard of Oz with a doodle of Dorothy, the Cowardly Lion, the Tin Man and the Scarecrow walking down the Yellow Brick Road towards a landscape with "Google" on it. Perhaps it's a metaphor.
Mary Shelley, the British author of Frankenstein, had the 213th anniversary of her birth celebrated by a spooky Google Doodle late last month.


http://www.telegraph.co.uk/technology/google/7986135/Google-Doodle-new-interactive-coloured-ball-design-sparks-web-mystery.html

the doodles are quite interesting.

Most importantly, did you notice that this new, as well as other similar ones, works only in webkit browsers (as in, not IE)?

He he, progressive enhancement at work.