The InQueue test federation will be closing — more details at InQueueShutdown.
InQueue is a "test/pilot" federation that has evolved with the core Shibboleth software to provide a testbed for institutions and vendors to pilot their Shibboleth deployments. As InCommon and other international federations ramp up, use of InQueue is expected to decrease.
While InQueue is fully functional as a demonstration of how real federations might work, it is not secure. Zero-assurance certificate authorities are common to InQueue deployments, and impersonation/spoofing is definitely possible.
Resources of value SHOULD NOT be placed behind InQueue-based service providers (such as this Wiki).