Is it possible to self-teach Linux?

I am an MCSE, MCITP and I have a bachelors, but I see many jobs that require knowledge of Linux. I'm curious though, it seems that linux is one of those things you either have to be obsessed with or work with everyday or there's no way to become good at it. Too many distros, too many different ways and command lines, and too much time needed to learn. Seems like it takes years and years. Is it possible for me to learn just enough to say I have some knowledge of using it? I have installed Open Suse 11.3 and Ubuntu, but i'm not sure if that's enough. What all do I need to know about those to have a general understanding of all Linux? Red Hat and Fedora seem more command based and difficult, must I know those as well or is Open Suse and Ubuntu enough?