[10PM] Additional thoughts and futures update -
 Much happens during overnight futures sessions as evidenced by the frequent gap open and the mediocre volume during the day. It is thus reasonable to duly emphasize the wave structure in futures. It has certainly been a frequent struggle to align the wave labeling in cash and futures, as so much of the wave structure gets kept outside of the day session.
 Wave 2 / Wave B (JulyLow-AugHigh-AugLow-SepHigh) is an upward flat rather than a zigzag. The connecting wave, AugHigh-AugLow, is too large to fit into a zigzag. An upward flat can accommodate greater upside potential as well, in theory.
 The following wave counts bring the SP500 cash index and its e-mini back in sync.
[Red] The top is in, with an expanding ending diagonal triangle, complete with an overthrow in the cash index. (It is less likely, IMO, on top of the observation that expanding EDTs are rare).
[Green and Blue] At this stage, these counts are practically identical - the difference between the two is due to ambiguities surrounding where iii has ended. Today's high is likely  of v.
As of 1012PM, ESZ0 has retraced 23.6% of .
[4PM] With the exception of the RUT, all indices have now conquered their respective August highs (and effectively the June highs). Even for the RUT, it is just a hair shy of from its June high (670.34 vs. 672.16).
As discussed in Taking Stock (9/17/10),odds continue to favor that the advance "since" the late August low will not be extending due to a lack of pullback in all indices prior to their August highs being exceeded(Chart 1, blue line, updated). [Thanks to George H for editorial help].
Market internals are decent during today's run-up (e.g. A/D). But volume and technicals remain less impressive despite the size of the advance. The likelihood that this is a third wave rather than a fifth wave is low.
The advance is very close to being complete based on its wave structure as well. I'll place today's high in SPX as  of v, with -down and -up to follow overnight and tomorrow morning (Chart 2).
A relatively less likely scenario is that the market topped today, which in the grand scheme of things does not make much difference. This possibility is looks appealing based on the wave structure in the RUT. RUT appears to be in  of v already (Chart 3).
Chart 4 and Chart 5 offer the corresponding wave counts on the Dec e-mini (ESZ0). The squiggle count shows the basis to label today's high as  of v.