I've started a table of CPU specifications as a google spreadsheet.
I'm mostly interested in the CPU clock rate, CPU caches, RAM bandwidth and size.
All these devices are very flexible, and are mostly configured with relatively small amounts of memory for embedded applications. However, they have a decently fast clock rate, and can interface to at least two SDRAM chips. These chips are 32bits wide and currently contain a total of 128MB each. The CPUs support up to 256MB per chip, so the next generation SDRAM devices can double overall capacity.
Compared to current "enterprise CPUs" they are much slower than Opterons but probably comparable to a single thread on a Niagara.
The next comparison table I want to put together is for board level devices, such as the Gumstix range.