The driver is released as source code under the GNU public license (GPL version 2.0 only). A version of this driver is included in the PCMCIA card services source code. In order to install the driver, it is necessary to compile the pcmcia package and install it. Currently, the latest stable version is the version in pcmcia-cs-3.1.20. It is version 1.70 of ray_cs with additional patches by David Hinds. Note that the version numbers of the driver were reset when it was included into pcmcia-cs, so the version number there will be smaller (at least for a while).
Since version 3.1.9 of the PCMCIA package, the ray_cs driver is included. The configuration of the driver included with pcmcia-cs is done in the /etc/pcmcia/config.opts file instead of the ray_cs.opts file. If you have been using ray_cs as a standalone package with older pcmcia-cs versions, then your config.opts file will not be overwritten by installing pcmcia-cs-3.1.10, and the configuration will still be in ray_cs.opts.