One of the main inhibitors to governmental adoption of "web 2.0" technology is the power curve and adoption models. Government tends to not invest in technology until the private sector has done so and figured it out some (though that doesn't help the government much in integrating it well). So until companies can figure out how to profit from wikis and other tools, don't look for it too much in the government. The more important factor is the government workers themselves, who skew old. Many government workers are actually technically savvie. However, getting the majority of workers to use a new set of tools is very challenging.
Of course, there may be a few hitches in this miraculous transformation. One caller who works in the U.S. federal government called in to Don today, saying something like, "I can't even get a replacement for my six year old computer—how will the federal government be able to transform itself with wikis?" Don basically replied, "Sure, there will be some cultural obstacles, but this sort of change is inevitable."