I'll add my own annecdote to this article. We had a wasp nest under the eaves of the house and I managed to successfully move them into a little hutch I built near the garden. I can't say I directly observed them saving the tomatoes, but we did have fewer tomato hornworms than in previous years.

They were also really docile and tolerated a good deal of me fumbling around with the nest. I waited until it was cold out and covered up pretty thouroghly, but they were mostly content to let me flop them around with a set of long BBQ tongs.