I've proposed the synonyms for mapping vcs to version-control and vm to virtual-machine. I figure we'll give it some time. If it gets voted on as approved by the community, great. If it's really close in a day or two and there aren't any objections, I (or another mod) can help it along by forcing the synonym.
Also, virtual-machine might need a clean-up at some point. It appears some questions are about virtual machines in a development environment while others are about the JVM or CLR virtual machines. It might be a good idea to consolidate into virtual-machine and then cleanup to consolidate into "jvm", "clr", other specific programming language VMs, and "virtualization". But we'll cross that bridge later.
As far as FOSS and open-source, I would need to dig deeper into how the tags are used and if there are any others related to open source software that need to be considered. On the surface, it seems like a good idea. I agree with the top voted answer in the question you linked to, but I'd want to investigate a bit more before making a final answer.