The Compute Module 3 contains the guts of a Raspberry Pi 3 (the BCM2837 processor and 1GB RAM) as well as a 4GB eMMC Flash device (which is the equivalent of the SD card in the Pi). This is all integrated on to a small 67.6mm x 31mm board which fits into a standard DDR2 SODIMM connector (the same type of connector as used for laptop memory).
At $29 for the module and $15 for the base board, this is how the Raspberry Pi should be priced.
The form factor is the SODIMM-DDR3 socket, which is incompatible with the Raspberry Pi Compute ecosystem.
This kind of begs the question:
What are the goals of a compute module? Is it to have a small, inexpensive computer in a permanent location? A lightweight but upgradeable CPU in something bigger? Freeing the RasPi's SODIMM2 form factor? Piggybacking on their ecosystem?
If the first two options, the Pine 64 is well worth considering. It appears to be more powerful, and is cheaper.
For the second two options, anything Raspberry Pi is the "best" because of the huge community behind it, head and shoulders above everything else, despite relatively lackluster performance.
Are there any other Compute modules out there, or similar systems? I am not aware of any.