If you somehow got complete data, you would be certain to find that Google employees received a large raise after these agreements were terminated (as others pointed out in this thread):
http://blogs.wsj.com/law/2010/11/10/on-googles-10-percent-pa...
That was something like 20,000-30,000 people, so if you consider it among the population of the 5 companies involved, it's extremely significant.
That was the largest raise I've received in a 13 year career in Silicon Valley, so I consider it anomalous.
But then you're back to the problem whether correlation is causation. You could conceivably argue that it was due to competition from Facebook, which was not part of those agreements.
In my opinion, salaries were depressed -- although how much and for how long is very hard to determine.