Mailtrust just held a discussion on Open Source Software in Business after hours tonight. It was open to the public, and we had a fairly good turnout, ~25 people.
Here are my takeaways.
A lot of people view closed source software vs. OSS as Microsoft vs. Linux. There are tons myths about open source and closed source, which can be very misleading to non-technical people. Since OSS is usually driven by developers fulfilling their own needs, the end product can sometimes be lacking important functionality. Many open source projects lack marketing, big surprise, so wider audiences don't realize alternatives to closed source projects exist. There are many ways to try and make money off OSS, such as different licensing or support. No one really thought the donation model is that viable in the long run. Nick V., a fellow Mailtruster, had a great point that OSS always has potential, whereas closed source doesn't.
As for what I think, let the best software win.