The Geekbench scores for just about every Intel Macintosh have been posted by Primate Labs Blog.
A total of 25 Geekbench test were run on MacBooks, MacBook Pros, Mac minis, iMacs, and Mac Pros. The scores ranged from 1472 for a Mac mini with a 1.5 GHz Core Solo to 5611 for a 3.0 GHz Xeon Mac Pro.
The author noted that, "There?s not a huge change in performance across most of Apple?s Intel-based Mac lineup (the high-end MacBook Pro Core 2 Duo is only 30% faster than the low-end MacBook Core Duo, for example). The only big changes occur at the low end with the (discontinued) single-core Mac mini, or at the high end with the quad-core Mac Pro."
These tests measured only the processor and memory performance, not graphics performance. This is an important distinction since the Mac mini and MacBook ship with integrated graphics/shared memory and have greatly reduced graphics performance compared to the high-end cards available for the Mac Pro.