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Maybe outdated now, but I thought it was interesting.