FlaCuda is probably a world's first CUDA-enabled FLAC encoder. It's opensource and licensed under LGPL. Current version is 0.8, published December 30th 2009.

Compared to reference flac 1.2.1 on Core i7 940, it runs approximately 10 times faster on GeForce GTX 285, when using higher compression ratios (modes -7, -8). FlaCuda -8 is faster than flac -0, and provides better compression than flac -8. Thanks to case@HA for the graph:

On this graph X-axis is compression ratio, Y-axis is encoding speed (vs realtime playback)

It is a .NET application, so you might have to install Microsoft .NET Framework.

CUETools.FlaCuda.exe [-0..-11] filename.wav [-o filename.flac]

List of CUDA-enabled devices
HydrogenAudio Forum Thread
Source code
Download (Linux)
Download (Windows)