In the Aperture 3 "Faces" view, when clicking on a person, there is a section "John may also be in the photos below". By clicking on the "Confirm Faces" button, you have the ability to click on each image to confirm. Is there a way to select multiple images or do this in bulk? I'd expect shift-clicking on the images to do it, but that doesn't work. There must be a better workflow.
Instead of clicking on the "Confirm Faces" button, simply select all the photos that match (using shift-click or any other method) and then drag them to the space above the grey bar that says "John may also be in the photos below". This has the affect of bulk confirming your selection as being John.
Another way of confirming (or rejecting) faces in bulk is to drag (option) select over the faces you want to confirm (or reject). You can even mix in the same drag by pressing or releasing the option key to change between confirm or reject.
Faces workflow has other tricks too (but nothing that makes its workflow smooth as one might expect in a pro app).
For instance, holding option when your ready to confirm the selections changes the Done button to Update, which will allow you to continue with other faces that Aperture finds immediately confirming after pressing it. It's more complex to describe than to play with:)