I've got a preliminary driver working for the CMedia 8738, 8768, and 8338 series of devices. This driver works with Boomer (you'll need RC3 installed, or -- hopefully -- Nevada build 115 when it comes out, and it seems to be working except for some issues with the record gain being a bit faint. (Hopefully I'll resolve those soon.)
The driver lacks support for advanced features like surround sound or jack retasking, mostly because I can't easily test them -- I have only an ancient 8738 -033 (stereo only) part available to me. (Also, it seems that CMedia has had some rather unusual changes with each revision of the chip, making proper support of advanced features such as SPDIF or surround sound a bit troublesome.)
So, that said, I'd like to hear from folks who have this part and can use a driver for it. If you want to test, drop me a line. Thanks.