I confirm that I'm very interested in exposing ATC as a WebGL extension, and the information below was the only missing piece. I will write a spec proposal very soon.
The interest in ATC comes from the fact that together with PVRTC it's one of the two widespread mobile generalist compressed texture formats, and while PVRTC already has a WebGL extension spec proposal, it alone isn't enough to cover most of the existing devices: at least Qualcomm GPUs do not support PVRTC. Thus in order for WebGL games to take off on mobile devices we need to expose both PVRTC and ATC, the latter being made possible by Diego's email.
On 12-09-07 12:15 PM, Wilson, Diego wrote: