$\begingroup$

UPDATE 2013-10-13

The latest update names B as CUSat 1 and C as DANDE. All payloads have now been identified. Interestingly, they say CUSat-2 is attached to the upper stage (object G). Everything after object G is identified as debris. Additionally, there are now 26 total objects cataloged, with debris pieces labeled H-AB.

It helps to understand what was expected in the first place. Here's a list of the payloads:

Cassiope (1 piece expected) - the primary payload.

DANDE (2 pieces expected) - According to their website, DANDE separates from the upper stage with a lightband adapter bracket, which then separates from the spacecraft itself. Apparently, this separation has not yet occurred, according to the DANDE team.

POPACS (7 pieces expected - 3 spheres, 4 spacers)

CUSat (only 1 piece expected - NOT 2 as reported elsewhere) - the linked article has details about the decision to keep them mated.

Total: 11 objects associated with the payloads. We can add one for the rocket body, bringing us to 12 expected objects, and 8 unknowns. The fairing was separated before the vehicle reached orbit, as is typically the case.

As @PearsonArtPhoto stated, Objects A-F would be the payloads, and G has been identified as the upper stage. In fact, it has recently been confirmed that A is Cassiope, and D-F are the three POPACSS spheres.

Now that that is all cleared up, it brings us to your actual question: what's everything else? To clarify, it is somewhat rare for a so-called successful launch to result in more tracked objects than expected, so the fact that there's even one extra object is noteworthy. @PearsonArtPhoto did a good job looking at the orbits of the unknown objects, so instead I'll focus on speculating about the source of the pieces.

SpaceX has not yet released much information about the upper stage test fire, other than there was an anomaly, and no explosion. The spread of the unknown objects is troubling - energy was added to them in some way - either through a short second burn (before it shut down) or via an explosion of some kind - even just a tank rupture. According to Jonathan McDowell, the delta-V for the scatter is about 60 m/s, which is quite significant.

A couple of the objects have/had very large decay rates, indicating that they are likely the pieces of insulation that SpaceX posited. However, many of the unknown objects have not yet decayed, so they likely have a higher ballistic coefficient (mass/cross sectional area), i.e. they are more dense than typical insulation. It's possible that there were other pieces associated with the secondary payloads, but something "coming loose" from an upper stage (and not causing other, bigger problems) would be a pretty egregious fault, and I think it's unlikely.

In my opinion, there was some sort of energetic event immediately following the upper stage firing attempt, resulting in several debris pieces.

Bottom line: SpaceX may not be talking much, but there are lots of people paying attention and trying to figure this out (including the Air Force... eventually).