It is the same in Germany. I always assumed it was that way everywhere.
If it's a 70 limit, and someone is in the passing lane doing 70, you'd still flash them.
(OK, there are speed limits on most patches of the Autobahn. But there are some without.)
And no, nobody passes on the outside. Even if you're about to exit and the rest of the lanes are moving slowly, you'll still slow down considerably and look a bit sheepish as you drift past the main highway traffic.
One problem here is that people driving the maximum lawful speed are still driving too slow for the prevailing speed of traffic.
For example, in the state of NY: Before you pass on the right on multilane roads such as expressways, make sure you check your mirrors, use the proper signals for lane change, and look over your right shoulder for other vehicles. After passing, be sure to check over your left shoulder, and to signal, before returning to the left lane. http://www.nydmv.state.ny.us/dmanual/chapter06-manual.htm
In Chicago at rush hour, if you leave more than a car's worth of space ahead or behind you, it will be filled instantly.
Whether or not it actually helps traffic, I couldn't say.
In the rare situations where this doesn't happen, I usually have a longer space than I actually need, so I just eat the difference.
If it's the former, he addresses that concern on his site.
I wish more people would check this site out. Traffic is a real problem that wastes billions of taxpayer dollars and hours on the road every year.
Another idea to make the roads better: lane-specific minimum speeds. Think about it. It would actually solve a ton of common traffic problems.