If you can't support the open-source system with in-house resources or through a vendor, then it doesn't make sense to use it. Where open source does make sense is by decreasing the amount of time it takes to implement a project by using an existing resource and modifying it to meet your needs. It also make sense to use open source in situations where the company doesn't have the big bucks to sink into a Cisco or Microsoft solution but needs similar functionality, ie Viatta, Apache, Asterisk, etc.

The decision to use open source has its strengths and weaknesses depending on the project.

I don't believe your article was very intelligently written. It only serves to rigurgitate the mindless drivel being spun by the very companies that stand to lose the most to open source.

BTW, I am not an open source zealot. I wouldn't use Linux for a directory server (AD) any more than I would use Windows for a firewall.