The articles linked by sdctcher are the first emtnione I have ever seen that manufacturers are allowed to post different mileage ratings than those provided by the EPA testing. All other stuff I have ever seen states that they are NOT allowed to do that, even though many would like to. So, not sure what the real situation is there.
Wayne, with all due respect for your hypermiling accomplishments, you are at the other end of the spectrum compared to those who have to do 0-60 in <13" as you state. While driving style has a lot to do with mileage, the type of driving that allows hypermiling IMHO can rarely be accomplished safely in real worl driving, in fact frequently it would be quite dangerous not just to the driver following that style, but to others as well.
Here are my owne observations comparing my 05 Prius to my previous car, an 03 MINI Cooper S. The MCS has EPA values of 25/32, a combined cycle 28 mpg.
I averaged 25 mpg, or 89.3% of the combined EPA.
In my Prius, I am currently averaging 46 mpg, or 83.6% of the combined 55 rating.
So, the Prius acchieves slightly less than the MINI in terms of percentage of EPA ratings. However, in the MINI I got 89% while driving in a very spirited manner, without any efforts at fuel saving, while in the Prius I get 83% while trying to maximize mileage within these constraints: 90% of my driving is very short hops, less than 5 miles (absolute mileage killers). I also drive with the flow of traffic for safety reasons, and on the freeway I don't drive slow, but usually between 75 and 80 mph. However, I do all else to maximize mpg, rarely use AC, moderate acceleration, adjust driving to traffic flow and lights to minimize acceleration/deceleration, etc...
The bottom line for me is: as well all know, EPA values are way off. I am also convinced that they are much more off for hybrids (or at least for the Prius), than for other cars. If I drove my Prius like I did the MINI, I would be at about 75% of EPA ratings, at best.
I do think the EPA should revise their ratings to reflect more realistic conditions.
At the same time, the onus is on consumers to do their purchasing research properly, and those who complain about the mileage they are getting in whatever car they have, are really complaining about their own lack of effort and research prior to buying the vehicle, IMHO. I don't think they shoudl blame the EPA, but I still think revised ratings would be a good thing.

Having said all that, I'm glad I switched to the Prius and am getting 46 mpg avg.
It's an awesome car, and I love all 'efficiency hybrids'. I'm less enamoured with 'power hybrids'.

Cheers,
M