I noticed this article today. 

GHash Commits to 40% Hashrate Cap at Bitcoin Mining Summit

http://www.coindesk.com/ghash-commits-40-hashrate-cap-bitcoin-mining-summit/

Here's a quote from Satoshi when the mining arms race began:

"We should have a gentleman’s agreement to postpone the GPU arms race as long as we can for the good of the network. It’s much easer to get new users up to speed if they don’t have to worry about GPU drivers and compatibility. It’s nice how anyone with just a CPU can compete fairly equally right now."

Maybe outdated now, but I thought it was interesting.