You’ll have to export (using LR4’s engine) before moving the image into Photoshop since “Edit in Photoshop” uses the current version of ACR to do the renderings with this command.
Well, actually, you don't have to "Export", but you do need to have LR4 render the image...
When you Edit in Photoshop command, you should see this dialog:
Select the 'Render using Lightroom' option.
If you selected a different option and checked the Don't show again option, then you'll need to reset your dialogs in the LR Preferences, General, Reset all warning dialogs.