A little over a month ago at a week-long coffee-infused hack-a-thon in-person gathering, many of our core developers worked on improving BRL-CAD's source code. The team inspected and fixed more than fifteen hundred issues being reported by Coverity Static Analysis*. Just released, the 2011 Coverity Open Source Integrity Report includes a two-page case study detailing our efforts. The free report is available (registration req'd) through the Open Scan Initiative website.
After five days of code crunching, the developers reduced BRL-CAD's defect density to less than 1/4th the industry average at approximately 0.22 defects per thousand lines of code (kloc). Since then, the rate continues to be reduced as the devs work on addressing 100% of the issues being reported as part of ongoing code cleanup and other code hardening efforts.
More details about the Coverity annual report are provided on their blog and in their press release. The report includes a comparison of commercial software to open source with rather interesting results (spoiler: open source wins).
* Coverity Static Analysis is one of the best static source code analysis tools available in the industry with a false-positive rate less than 10%. While normally and substantially paid-for software, Coverity provides cost-free scanning and consultative assistance to open source projects as part of the Open Scan Initiative. The Open Scan Initiative was initiated in 2006 by the Department of Homeland Security and continues as infrastructure owned and operated by Coverity.