Open source is profitable in two ways:
1. If the work is ultimately for a company you are working for fulltime and getting paid from the start. This is the case with IOS support for DeviceFarmer. I work fulltime for T-Mobile. I am thankful to them for allowing the majority of the resulting software to be open sourced. The reason they allowed it to be that way, and wanted it from the start, is so that we can benefit from users using the software, finding bugs, and reporting them. There have been contributions from the open source community to it as well that have been very helpful.
2. By providing paid support for an open source project. There is a great need right now for someone ( and/or many someones ) to work with companies to get DeviceFarmer setup and working well for their needs. I do this a little bit on the side myself, but it is tricky because I don't have much time remaining after my day job to do so, and I have to be careful not to let it become a conflict of interest.
DeviceFarmer as a entity is a collection of key personnel who have been maintaining OpenSTF. I believe all of them are fulltime employees of various companies that use it internally and contribute to it to address their own needs. I joined the core team as a result of writing IOS support for it ( I say "writing", despite also porting in a large chunk of IOS support from other open source contributors; mrx in specific )
Right now DeviceFarmer isn't a legal entity. There is no company or non-profit currently. It is just a bunch of developers cooperating. We have considered creating a non-profit company for it, but it has not been done yet. The members of the group are spread out internationally.
The original main author(s) of OpenSTF formed the company HeadSpin out of it, and offered it as a commercial project. Very recently the company collapsed as a result of internal corruption, but the project itself lives on. Really they had abandoned OpenSTF 2-years ago anyway. The rebranding to DeviceFarmer instead of OpenSTF is to move the project to being open and no longer restricted by HeadSpin.
HeadSpin themselves refused to ever accept contribution of IOS support into the OpenSTF project, because IOS support was one of the main differences in their commercial offering. They refused to ever open source that portion of OpenSTF. Forking the project was necessary to allow this. Essentially the entire community has moved to the fork and abandoned OpenSTF. The crumbling of HeadSpin sealed the deal and OpenSTF is essentially no more.