"The seven companies with the youngest workers, ranked from youngest to highest in median age, were Epic Games (26); Facebook (28); Zynga (28); Google (29); and AOL, Blizzard Entertainment, InfoSys, and Monster.com (all 30). According to the Bureau of Labor Statistics, only shoe stores and restaurants have workers with a median age less than 30."

http://bits.blogs.nytimes.com/2013/07/05/technology-workers-...

Of course, it depends on the company/product/founders/etc.