All of this information was obtained from the Federal income tax forms all U.S. non-profits are required to file with the IRS. Specifically, Form 990 (or the 990-EZ when applicable). Thirteen of the non-profits have publicly available information for their 2010 fiscal years, with the other five's information only up to date to their respective 2009 fiscal years.

Given that we're in 2012, why the delay?

Part of the reason is the variations in fiscal years. If these are offset from calendar years, then this would be a reason for the extra time.

Non-profits have an additional reprieve: they can file a Form 8868 and get an automatic three-month extension for filing their returns, no questions asked. And, after that automatic extension, the non-profit can file for an additional three-month extension if they can show good reasons why.

So, this means that the Mozilla Foundation didn't file their 990 until Oct. 5, 2011 with the Linux Foundation filing in just before that on Sept. 31.