- Professionally? Yep, I primarily work with PHP and that means running a LAMP stack almost always. Once in a while we run on Windows which isn't a big deal, but that's usually only for intranet sites.
- As a hobby? Yes, I have a Linux "play" box, but nothing desktop-related - it's just a server/headless.
- Dual boot? Main OS? Separate box, but don't do much actual work on it - my development machine is Windows and I use it as a git repository more than anything.
- What distro(s)? Ubuntu and CentOS mostly. I rarely ever touch anything outside of these two.
- What are your specific interests in Linux? I enjoy knowing how to do my job on all the environments I might need to operate on/with. Being a freelance developer means also being part sysadmin, so knowing how to do things like setup postfix and dovecot and manage a fairly basic LAMP stack that doesn't have too many complex pieces is virtually required. I also enjoy tinkering with new stuff from time to time and like learning how to do something I didn't know how to do before, or learn how to use new tools that make my job better (like monit for making sure crap doesn't die and I don't know about it, which I only started using recently).