That sounds like jibber jabber, but it is all true. Mostly a release to add new cameras, but as always I update anyway as you never know what little tweaks have been made along the way.
Here is what Adobe says is new:
Support for the following cameras has been added in this update. Visit the Camera Raw page for a complete list of supported cameras.
Canon EOS 5D Mark II
Canon PowerShot G10
Leica D-LUX 4*
Here is a link for the windows Download.
And the MAC download too.
If you have yet to buy CS4 and you read this post anyway, you are the best and here is a link to Amazon just for you!.