Wired reports that Stanford is releasing a studying showing that Linux has 0.17 bugs per 1000 lines of code, where commercial software typically has 20 to 30 bugs per 1000 lines of code.
Source: http://www.testgeek.com/cgi-bin/blosxom.cgi/2004/12/14#BugCounts
Source Location: http://www.wired.com/news/linux/0,1411,66022,00.html