Starting point:

I have some notes from Dan and Phillippe as follows:

 Background: SNAP-12 standard (roughly one gigabit regime)
 When evolved to about 12 gigabit things get proprietary
 wind up with miniPOD technology

 miniPOD connects with right-angle optics.  Other end may be a 
 number of other things, including MTP or MPO connectors that
 come from a variety of suppliers (including AMP, 3M, Molex, etc)

Dan and Phillippe have compiled notes at:

 http://www.pa.msu.edu/hep/atlas/l1calo/reference/other/optical/

In /transceivers/snap_12_rev_1.1_specification.pdf I quote:

  The pluggable parallel optical modules shall accept a 
  MPO optical connector that conforms to IEC 61754-7

Language from MOLEX website:
  VersaBeam POD terminations can be aggregated to 24-, 48- and 72-fiber MT ferrules
  High-density connections achieved with Molex HBMT™, Array and Circular MT connectors

  Multiple 12-fiber VersaBeam interconnects can be consolidated 
  to a single I/O assembly on the front or back panel by using 
  either 24-, 48-, and 72-fiber MT ferrules in Molex’s high-
  density interconnects including HBMT™, Array and Circular MT 
  connectors.


Search Term: Circular MT and array assemblies on MOLEX site.

Molex's Array connector and adapter system is utilized 
on the card front panel or chassis back panel. Robust 
polarized guide pins ensure consistent and repeatable 
mating. Multiple back shell options allow system design 
engineers to customize their cable management strategy. 
A high-density interconnection is achieved by increasing 
the number of MT ferrules in the array connector either 
as a single or dual row of 4 to 8 MT ferrules per row. 
The individual MT ferrules may be populated with 4, 8, 
12 or 24 fibers depending on the optical requirements. 


What I've learned so far:

MT ferrules can carry 4,8,12 or 24 fibers per ferrule.