Dear Ben,
I've been quite interested in the idea of compiling a list of companies into Wikidata. I wanted to see how well this fits with Wikidata's goals. There are company databases like Hoovers/DNB, Mattermark, LinkedIn, Crunchbase, DataFox, etc. which are very popular, but not as open as Wikidata. These sites are hugely valuable to folks like investors, job candidates, sales organizations, etc. and I'd love to see an open collaborative approach.
Are you aware of the http://wikirate.org/ community? This is a EU research funded project.
Raphaël