Since ALSA 1.0.18 RC3 there were quite a few improvements to the Oxygen driver for some high-end C-Media APUs, many HDA Codec driver improvements including support for HDMI audio on the NVIDIA MCP78/7A, ALC1200 / ALC887 support, and many driver updates from the Google Summer of Code projects.
The change-log between 1.0.18 RC3 and 1.0.18 final can be read here along with the complete change list. The source packages for ALSA 1.0.18 can be downloaded here or wait for it to hit your distribution's package repository.
While an X-Fi ALSA driver (based on the Open Sound System X-Fi driver) appeared last month for the Creative X-Fi sound cards, this driver has yet to be stabilized and merged into ALSA. This may come though with the ALSA 1.0.19 release.