Want a promotion? Write open-source software
CIO.com's Esther Schindler suggests the perfect way to boost a career: Get involved in an open-source project:
Sometimes, there isn't much you can do to kick-start your career. Not everyone can be lucky enough to get involved in a high-profile project at work, or to develop a talent in a technology that's suddenly in-demand. But it surprises me when IT professionals who aim to move up the career ladders don't take advantage of one resource that's a win-win solution all around: get involved in an open source project.
As Esther writes, open source is a great way to circumvent office politics, which tend to rely on "who you know" rather than "what you know." Open-source communities, while not perfect on this score, generally offer a meritocracy: You're as good as your code (or other contributions). It's a great way to prove what you can do.
As a bonus, open source savvy developers tend to make up to 40 percent more than their proprietary peers. So, untold fame, more money, etc. What's not to love about open source?
Ah, yes. That work/life balance thing. Well, you always have retirement during which you can relax. :-)


By the way, if you're interested, my software is an open source Zigbee protocol stack. If you don't know what that is, it's basically wireless sensor networking. Here's my shamelessly self-promoting link: www.freaklabs.org
Correlation and causation are a tricky business. The only study I know off that addresses this "correctly" (but then they never seem to have finished it) is this one: http://opensource.ucc.ie/icse2002/HannRobertsSlaughterFielding.pdf
I guess your point so far has evaded proof.
Contributing is a different story however, often being enough of a benefit to not go full-time with OSS.