San Francisco media artist Takashi Kawashima has been exploring crowdsourced art for a few years, now.
For example, Takashi's 2005 project "The King Has...", a collaboration with Krister Olsson, invited people to text the artist(s) their most burdensome secrets; these secrets were then posted (anonymously) in a public place. Video below:
Between November 2007 and March 2008, Takashi collaborated with Aaron Koblin on "Ten Thousand Cents," a "coordinated, crowdsourced [digital] art project" created by several thousand individuals using Amazon's Mechanical Turk service — a crowdsourcing marketplace, publicly launched in 2005, that enables computer programs to coordinate the use of human intelligence — and a customized Flash-based drawing software.
Koblin and Takashi divided a high-res scan of the $100 bill into 10,000 equal parts, each of which was delivered to a "turker" who was paid a penny to duplicate it using the drawing tool. Contributors (who hailed from 51 different countries) didn't have any idea of the whole picture. The project took 5 months to complete; the idea was to use 10,000 turkers, but some turkers participated more than once. The end result was a reproduction of a $100 bill that cost $100 to create. Video:
There's a neat interface here that lets you watch any one of the 10,000 Flash paintings being created. "Ten Thousand Cents" was a finalist (Experimental category) for a SXSW Web Award in 2009.
More recently, Aaron Koblin and Daniel Massey collaborated on "Bicycle Built for Two Thousand" (great title), which used Amazon Mechanical Turk to record 2,088 sound clips. Turkers were sent a short-short sound clip — snipped from a mechanical-speech version of the 1892 song "Daisy Bell" — and asked to imitate what they heard, using a custom audio recording tool in a web browser. They were not given additional information. People from 71 countries participated; they were paid six cents apiece. Stitched back together, the clips sound like this:
Why a mechanical-speech version of "Daisy Bell"? Because the song was used, in 1962, as the first example of musical speech synthesis. (That's also why HAL sings it, in 2001: A Space Odyssey.)