Although my background has been extensively commercial software such as Microsoft Windows (XP, 2000/03, Active Directory) CITRIX, Novell, Lotus etc., for the last two years I have done more and more with Open Source software when building infrastructure.
As the various projects mature, they bring an amazing amount of stable, feature rich services to the enterprise.
If you are interested in some of the best projects out there, check out these slide shows and information from eWEEK.
In our current endeavors we are using the following from the eWEEK list:
- OpenSSH & SSL
And probably the most exciting, are currently developing IP phone systems (VOIP) around Asterisk!
All good stuff and I encourage you to check it out.