Just come back from a seminar on the polarisation of the CMB using WMAP and QUaD data... nearly recovered.
WMAP provided a lot more than just the temperature map. The major concern for cosmologists at the time wasn't that the data had to be rough to a certain level, but that it had to be smooth to a certain level - roughly one degree in the sky. This is due to inflation bringing certain effects from particle physics from the plank scale up to their current scale. There was an upper limit on inflation and so an upper limit on the variations. The fine detail hadn't been worked out as closer examination of the initial conditions of the universe were required, and as of yet the information hasn't been collated.
A temperature profile
was also produced by WMAP, whose shape fitted in extremely well with the cosmological models of the time - and this is a more important facet of the work. The initial part of the curve is due to scattering of photons in the early universe. There are then oscillations predicted and observed to do with ordinary baryonic matter oscillating in dark matter created gravitational potentials. The fit of the baryon oscillation theory model to WMAP data is incredibly good. The final part of the graph shows the oscillations dying away as the universe expands and dissipates and everything settles down and stops oscillating. This part of the theory doesn't get alot of attention as it isn't exactly the easiest bit of science communication, but it holds the tentative evidence that there has been an inflationary big bang event. I am very interested in the far left of the graph, were the really early bit of the universe seems to diverge from the standard cosmological model. But as you say, the European Planck probe will be an order of magnitude better than WMAP so better reserve judgement from that point.
But the real fun begins after this. Cosmologists don't need the universe to be flat, they merely need it to be quite near to flat for their models to agree with the current observations. 'Quite near' is the sort of vagueness that now sets in as all further graphs probing the early universe begin to suffer from not being accurate enough to tell between one model and another.
WMAP seemed to give both a lot of confirmation as well as consternation to the cosmological community, suddenly required to fit their theories to observations that simply weren't imagined when the theories were set up. Planck will further muddy the waters, I suspect, killing off some of the areas of doubt.
Of course, all data released to the public contains a number of assumptions, some reliable, some not, about what has happened to the data in transmission. In this case, we're talking about the passage of photons in the past fourteen billion years or so, during which they are gravitationally lensed, scattered, shifted and all sorts of other horrors occur. Modelling this foreground could be another way of proving/disproving what the WMAP team say they see.
The current best models have both Dark Energy and Dark Matter in them because that is what the data interpolating the model's results says there should be. Whether that is due to a philosophical problem, a data problem or an analysis problem or if it is a real effect, only time and a lot of analysis and rejigging of the models will tell.
At the moment, there are a large amount of different theories using effectively the same model but with different paramters in them. Cosmologists have narrowed down and constrained the parameters a little, but until they and their nature are really nailed, there won't be a single model brought out and the arguments over what the data shows with repect to the standard models always seem a little bit of a curate's egg, with the final refrain being "I'm sure when [insert handy new mission here] sees first light, we'll be able to constrain [insert effect, parameter or unfeasibly large error bar on graph here] a little"
As for all these "unexplained" things like star formation, inflation and exact temperature variations on the CMB - at least two of these are particle physics problems, not cosmology. Cosmologists are there to say "we see inflation" or "stars could've formed at this time" rather than "the mechanism for this is..." they're big picture people, and others deal with the minutia. At least, that's how it looks to me.
Still, gives me something to listen to and be glad I'm not a cosmologist. At least if we are reaching the limits on what we can learn from the Big Bang model, we have people to seek out that information and base the next step, if needs be, on it.