Not true. While Abrash seems to makes this claim several times early in the PDF [1], near the end there's this:
> In addition to the question of how games will interact with input, rules about how players can move around a virtual space without getting motion sick or losing presence have yet to be figured out. We’ve found that traditional FPS movement is far from optimal and tends to cause motion sickness, so VR may be best with slow movement and a lot of up-close interaction, in which case we’ll have to learn how to create fun games around that.
Abrash admits that "traditional FPS movement" still makes people sick despite all the technical improvements touted earlier in the paper. His solution doesn't work for FPSs but instead proposes new types of games instead of the ones that people want to play. Flying fighter jets, the type of simulation that gives simulation sickness its name [2], does not involve the "slow movement and a lot of up-close interaction" that Abrash says is needed to prevent sickness.
Like you I was excited that Valve had solved the simulation sickness problem, but on closer reading found that it's just not true. Many people have the desire to use VR tech in virtual worlds doing things that involve normal-speed head movements without getting sick, but Valve has not solved this problem.
[1] http://media.steampowered.com/apps/abrashblog/Abrash%20Dev%2...
[2] http://en.wikipedia.org/wiki/Motion_sickness#Simulation_sick...