Apple used to have a standard Apple PR site Apple.com/PR which allowed all the access to the image artwork for the latest products. If you try that url it will take you to the Newsroom website. Below are some useful sites within the web to help location the information you require.
- Apple Newsroom (Apple)
- Marketing Resources and Identity Guidelines (Apple)
- Product Bezels (Apple)
- Apple Design Resources (Apple)
- Desktop Images (from BasicAppleGuy)