IBM has published information for developers for making a switch.
This is a roadmap for developers making the transition to Linux. A little old document but still quite useful.
This roadmap is designed to help you take the experience and knowledge that you already have in computing and redirect it to working in Linux. It's not the only reference you'll ever need, but it will help you get past some of your first obstacles and adjust to a new and, I think, exciting approach to computing. As you follow this roadmap, you'll discover many new resources to help you learn, troubleshoot, and manage Linux.
It covers following topics:
Step # 1: Thinking in Linux
Step # 2: Console crash course
Step # 3: Introduction to Webmin
Step # 4: User administration
Step # 5: Linux logging
Step # 6: Working with file systems
Step # 7: Networking
Step # 8: Backup and recovery
Step # 9: Installing software