No. There will be no more ACR updates for Photoshop CS4. That version is no longer supported. You can download the DNG converter and convert your images to digital negative files that can then be opened in the ACR that you already have. Since your camera is so new I'm not sure if it's even supported by the DNG converter. You might have to wait for the next update.
Your other alternative would be to upgrade your Photoshop. Of course, that will cost a little money. But not nearly as much as your new camera did.
The Nikon D800 is listed as a newly supported camera for the beta ACR 6.7 RC on Adobe Labs, which means the corresponding DNG Converter 6.7 RC would be what you’d have to use to convert your files to DNG so they’d open in an older Photoshop’s ACR.