The poll question was "Which Linux distribution do you use most commonly for production deployments of Apache Karaf 2.x?". LinkedIn only allows up to five options, so I choose four of the major Linux distributions I've seen in production use, along with a catch all 'other' option. In a sample size of 17 respondents 59% were deploying on Red Hat Linux, with 35% on a Debian/Ubuntu based system, and 9% on Suse.
As the sample size was small we obviously can not draw any conclusions, however as these numbers come from a Karaf users group I believe they hint at a common usage pattern of Red Hat and Debian/Ubuntu based system preference. The utility of these results really resides in the knowledge that there are other users out there working with Karaf on these platforms - you're less likely to be the first to encounter a platform specific issue, and if you are than you know there is a community out there that will want to see the issue resolved as quickly as possible.