UPDATE: I've added transaction support to the script. Previous to this you would have lost a message if something had gone wrong. PS does not support TransactionScope, so we had to use MessageQueueTransaction.
The ReturnToSourceQueue.exe tool that comes with NSB presented a challenge to us when we tried to deploy it on all our app servers. We needed to schedule an on-demand job to run the tool by our Operations group. Since the agent we use goes on each machine and is not cluster aware, this presented an issue. Our resolution was to replicate the same functionality in PS with a bit of a twist. We added the ability to hit a remote queue. The script was done by one of our developers Brandon Moriarty and I've posted it to GitHub for everyone to enjoy! Big thanks to Brandon for whipping this one up. Don't forget I have a few other PS scripts in there to do some quick and dirty things with MSMQ.