No, you're not missing anything -- I was just saying that it would be a shame if people still can't code preemptively scheduled parallel apps when the average home gaming machine is going to have 16 cores soon and that many devs (me included) are looking to buy a 32/64-core workstation. Nothing else. :)
Really exciting that preemption is possible. Thanks for your insights!
We can do preemptive scheduling of user-level threads by registering a timer interrupt with the OS and preempting the currently running user-level thread in favor of another one. This is up to the individual libraries to implement. These issues are discussed in [1] Sec 4.3.