I recently got a Wildcat VP 760 for testing compatibility on. Unfortunately, it does not seem to expose EXT_texture_compression_s3tc, nor support it if I blindly turn on the enumerants.
I sent a question to their customer support, who replied back saying they support the format, and please download the latest drivers. Well, I thought I had, but I tried again. Same result - no extension, no support.
This time, I sent a little sample program to the customer support people that I’d expect to work, and which doesn’t, but that was a while ago and I haven’t heard back from them.
Seeing as the Wildcat support DX8.1, they should support DXT1/3/5, and seeing as they do that, OpenGL extension support should be simple. If anyone wants to try the app, it’s available here: (with source)
http://www.speakeasy.org/~hplus/s3tctest2.zip