Enterprise wide command task scheduler: suggestions?

Got a fairly tall-order task. I'm looking for a utility (at a
reasonable price point $0 even better) to do remote task management
for 800-1000 linux systems. Our support staff needs to be able to
issue a single command from a central location and have the task run
across multiple nodes in the system. The systems are bunched into
loosely coupled groups that do different tasks.

I need a task management utility to run a command across groups of
systems and return the output & exit status to the central console.
Even more beneficial would be expect like capability where I could do
a wait for command to finish before continuing to next command; for
any interactive commands that I need to run across 1000 systems;
without having to manually login to each system to type a response.

Any help would be beneficial