I think most of us feel that sensor dynamic range (DR) is an important thing to assess in a camera. Is anyone doing it well? Of all the sites which tell us about DR on one camera vs another, I just don't have confidence in any of their methods. I don't mean any offense to any of the reviewers on the big sites, not that they're reading this anyway =). I'll try to explain myself here as well as I can.

I'll start with the table found 2/3 way down on this page at Imaging-Resource.
Those results just don't remotely jibe with my real world experience having owned or extensively used a bunch of cameras on that list. Furthermore, their methods - using the lowest ISO possible for each camera and different ACR versions for different cameras - just don't strike me as valid.

Next, consider DPReview. First look here, where Phil Askey, Editor of DPReview, had the following to say regarding the DR of the 5D versus the 40D: "Naturally the 5D's full frame sensor is going to give you better DR, IQ will depend more on your lenses than the camera." Now after reading that, look at what the DPReview 30D and 5D reviews show for dynamic range here, here, and here. Their testing method shows essentially no difference in DR between the 30D and the 5D.

Most like to say that DR correlates best to pixel size/density. That agrees pretty well with my real life experience, but not all that well. My 4-year-old camera with a 5MP 2/3" sensor seems to hold it's own in DR with my new camera with a 10MP 4/3" sensor, which has half the pixel density. I may be wrong about that; it's a preliminary opinion based on regular shooting without any rigorous testing. My old Fuji F30 had a lower pixel density than many of its competitors, but DR always seemed to be in limited supply with that camera. I'll chalk that up to in-camera processing since there was no RAW file available. My personal experience, again without rigorous testing, is that the 5D has noticeably more sensor DR than the 30D. Still, none of the rigorous testing on DPR and other sites seems to demonstrate a tight correlation between pixel size and DR.

Here's how DPR measures dynamic range in their words. From the 5D review:
"Our new Dynamic Range measurement system involves shooting a calibrated Stouffer Step Wedge (13 stops total range) which is backlit using a daylight balanced lamp (98 CRI). A single shot of this produces a gray scale wedge from (the cameras) black to clipped white (example below). Each step of the scale is equivalent to 1/3 EV (a third of a stop), we select one step as 'middle gray' and measure outwards to define the dynamic range. Hence there are 'two sides' to our results, the amount of shadow range (below middle gray) and the amount of highlight range (above middle gray)."

Sounds great, right? I think it would be fair to say that based on the DSLR test results on this DPReview, the Fuji S5 has the most DR, the Oly E-410 the least, and all the other DSLRs about the same. JPEG results don't matter much to me as I shoot almost exclusively RAW. Also, JPEG results don't tell us as much about sensor DR. Here's the deal from the E-410 review conclusion: "Secondly we were kind of disappointed with the dynamic range performance - dropping three quarters of a stop of highlight range can be the difference between a beautiful blue sky and one which is white and washed-out". Now take a look at the "RAW headroom" graphs on this page from the E-410 review and this one from the 400D/XTi review. I don't see where this 3/4 stop highlight loss is coming from. Even in their JPEG performance curves, it doesn't look like 3/4 stop (except vs the Canon), but in RAW - where it counts IMO - it's almost a dead heat.

I'm no Olympus fanboy. In fact, as I alluded to above, my early impression with the E-410 is that DR in RAW is more limited than I had expected it to be. However, I believe the following are probably true:
1) None of the major review sites are assessing DR in a way that helps us learn what we need to know.
2) The commonly taught principle that sensor DR correlates very closely with pixel size, while as useful a way as any to guess about a given camera's DR capability, is probably far from perfect in practice.
3) Perhaps some of us should give greater consideration to how lenses can maximize delivery to the sensor in such a way that makes the most of the sensor DR we're given, whether that be using ND Grad filters with a bright sky or keeping around an old, low-contrast prime for a day of digital black and white.