Have you manually gone to the update site to see what is available for CS4?
All Adobe updates start here and select product, read to see if you need to install updates in number order, or if the updates are cumulative for the individual product http://www.adobe.com/downloads/updates/
Since CS4 is now 3 versions old (CS5 CS5.5 CS6) my best GUESS is that there will not be any updates... but since I don't work for Adobe, that is only a guess
Looks like you need to find a file converter, or shoot in JPG instead of RAW, or upgrade to CS6... which, of course, might mean a new 64bit computer (Oh... you are Mac... I have no idea how things work on that side of the aisle)
The support for newer cameras is the domain of ACR, and from time to time, compatibility with older versions of PS are often dropped.
One option would be to use the free Adobe DNG Converter.
You are correct. Photoshop CS4 will not see any updates. ACR (Adobe Camera RAW), the plug-in, is constantly being updated, but as it gets re-written, there are times, where older versions of PS can no longer use it. ACR has new camera RAW versions added with each upgrade, so if one buys a new camera, it might take an update to ACR, for that camera's files to be supported. That ACR update might, or might not, work with older versions of PS. ACR is written for the current version of PS, and once it progresses to the point, where an older version of PS cannot use it, support for it in that older version will not happen.
- Upgrade PS to CS 6, and install the latest ACR
- Purchase the latest Lightroom version and install the latest ACR
- Download and install the free Adobe DNG converter, which does not rely on PS as a host, like ACR does
Good luck to the OP,