It's a field of heavy-hitters. The 4004, 8088, and Opteron 240 each ushered in a new age in microprocessors.
It was the one that finally lifted intel in peoples viewpoint. I think that a lot of people fail to realise just how much of intel's product lineup in the last 14 years can be traced to the P6 microarchitecture.
It could even be one of many technologies recently on the market. "Influence" is a legacy; you can't see it on launch day. Maybe one day we will look back on hUMA [0] and say it was one of those Things? The PS4 processor in particular, as the first processor with hUMA.
Although, it does look to me like innovation is more gradual now just as a matter of fact- the business cycle is much shorter now. The 4004 was released in '71, the 8088 in '79, but today every chip vendor releases a new chip every six months, so changes will naturally be spread across releases and it will be harder to point and say "There, right there, that is where the world changed"
[0]: http://en.wikipedia.org/wiki/Uniform_memory_access#hUMA
Realize that's still x86. I'm not sure we'll see that change, though. Another hugely influential Intel chip is behind that story: Itanium marks the point at which it became clear that the market's no longer receptive to completely new ISAs in general-purpose CPUs.
Also, markets change. Today, 'normal' people don't care about CPU architectures. Who cares what his phone runs on, as long as it runs with low power use?
EDIT: They're releasing explanations as they submit patents, so not everything is public yet. I just submitted the most recent talk.