This is a decompiled view of how the PowerShell provider (specifically it's TypeManager class) for IIS attempts to provide consistency btwn the execution of a command and the commits actually being written to disk in applicationHost.config. All kinds of fun ensues when committing the changes to disk doesn't actually happen within that one second…

TypeManager.CommitChanges.cs

public void CommitChanges(bool doCommit)
{
    if (!this.InCommitDelay() && this.WritableServerManager != null)
    {
        try
        {
            if (doCommit)
            {
                this.commitSynchronization = new AutoResetEvent(false);
                this.WritableServerManager.CommitChanges();
                this.commitSynchronization.WaitOne(1000, false);
            }
        }
        finally
        {
            this.commitSynchronization = null;
        }
    }
}