It was shown at festivals in 2009 (as a work in progress) but the director and producer disagreed about the final edit.
A version of the film (I believe the editor's version) premiered in Europe and was released on DVD 2009-2010
It was released on DVD by a Canadian company in 2010 and copies flooded into the US, making it harder to find a US distributor. (I checked out Mr Nobody (Canadian DVD) in Feb 2011 from my local library). I have emailed HSX over the years showing them listings of the movie available at major libraries across the US but they chose not to dead delist it.
Mr Nobody was just recently (last summer?) picked up by Magnolia and given a VOD release before getting a small limited theatrical release.
There are currently two versions of the Mr Nobody Magnolia release... 1 is Mr Nobody Theatrical Cut (probally the producer cut) and 1 is Mr Nobody Extended Director's Cut (which I can only find available thru VOD):
http://www.amazon.com/Mr-Nobody-Theatrical-Jared-Leto/dp/B00FG5E03W/ref=sr_1_1?s=movies-tv&ie=UTF8&qid=1397582001&sr=1-1&keywords=mr+nobody
http://www.amazon.com/Mr-Nobody-Extended-Directors-Cut/dp/B00IMZ0PM8
Here is an article that describes the differences between the two edited versions:
http://www.movie-censorship.com/report.php?ID=267603