Recently I posted about a conceptual mashup of commercial SaaS and OpenSource. Asim Baig of Cats says this;
CATS (http://www.catsone.com) is an example of SaaS and open source in complete harmony. We provide the Applicant Tracking System to thousands of companies, HR departments, staffing and recruiting agencies. We also give away the source code under a modified Mozilla Public License. We estimate 18,000 instances of CATS in 120 countries. As of this writing we are also hosting over 1000 companies on our SaaS platform.
It sounds like a dream combination and adds real world credibility to (what was admittedly) a conceptual post.
Good work CATS!