When was the first GPU miner made available publicly? The GPU miners are widely used nowadays, but that wasn't always the case. When was the first GPU mining software made available publicly?
This post from SmokesTooMuch seems to be the first time GPU mining was suggested:

Suggestion :
Since the coins are generated faster on fast machines, many people will want to use their GPU power to do this, too.
So, my suggestion is to implement a GPU-computing support using ATI Stream and Nvidia CUDA.

Here's satoshi in December 2009 asking for people not to use GPUs to mine:

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.

So it seems the idea was around for a long time before the savages broke the gentleman's agreement.  :)