New guest post up on Photofocus.com on Two Fast Ways to Apply Develop Settings to Multiple Photos in Lightroom. Here’s the steps I use for applying the same crop to multiple photos:

1. Press G to jump to Grid.
2. Select all the photos you want to have the same aspect ratio.
3. Expand the Quick Develop panel
4. Expand the Saved Preset section if you can’t see the Crop Ratio setting.
5. Click the Crop Ratio drop-down menu and select the aspect ratio or Enter Custom to create your own.

All the selected thumbnails will update to the new aspect ratio. Press R if you want to jump to the Crop tool and tweak the crop composition.