Given that install/inventory/reservesys are necessary for a functioning beaker installation, either all three should ship with beaker (or in an associated package) and be automatically added, or the deployment guide should be more explicit about obtaining them and adding them.
Agreed that bundling the tasks somehow would be nice, but I'm not sure how we could sanely update them in that case. In the meantime, the docs are now explicit about needing to add these tasks after setting up your Beaker instance: http://beaker-project.org/docs/admin-guide/installation.html#next-steps "There are two special tasks which Beaker relies on for normal operation: /distribution/install and /distribution/reservesys. You should add these to your Beaker installation before attempting to run jobs. [...]"