Let's tally up the list:
- Zimbra - $350 million (on $6 million of trailing revenues, on track to hit $20 million in 2007) - September 2007
- XenSource - $500 million (on $1 million in trailing revenues) - August 2007
- JBoss - $350 million (on $27 million in 2006 revenues) - June 2006
- Sleepycat - $35-50 million (on ~$7 million in trailing revenues, is my best guess) - February 2006
- Gluecode - $10 million (on very little in trailing revenues, less than $1 million, I believe) - May 2005
- SUSE - $210 million (can't remember revenues - I think $30-40 million) - November 2003
- Ximian - ~$50 million (I can't remember - on $1 million or so in trailing revenues) - August 2003
What's the trend? Bigger. We are in the midst of a Gold Rush, as Dana Blankenhorn has written. The rules of software business are being rewritten, and those who understand them will make a lot of money for shareholders...and themselves.
While the early days of open source saw a few wild valuations (Ximian comes to mind, though I still think it was a good move by Novell, as it brought open-source DNA to the company), it's only recently that we've seen open source break $100 million valuations on very little revenue.
Clearly, the market feels like the best is yet to come.
And so it is. Now is a fantastic time to be involved in redefining the software industry to one that focuses on customers, not licenses. You should join.
Updated with a more accurate picture of Zimbra's 2006 and 2007 revenues.