I work for the federal government, and I work with (but not for) HP/EDS in the building, as they supply the majority of infrastructure services to this agency (including Active Directory, DNS, core and edge network, etc.) While HP is a competitor to me here, we work cooperatively more than not, and I've never had an issue where another contractor was the impediment. Conflicting, or impossible-to-meet requirements are…
So far, I've only worked for one organization that was genuinely more convoluted, irrational, and technologically backward than the government... and that was amazon.