I read over at dpreview.com that Casio has released a firmware update, version 1.02, for this camera. Instructions and download can be found here (North American Users) or here (for users outside North America).
The site says that this firmware update fixes the following:
Improvements Provided by This Update - V1.00-V1.02
� Improves white balance performance.
� Fixes a problem that occurs in the Voice Recoding Mode when memory becomes full.
I have seen complaints about a bluish tint with flash. I've noticed this on a few of my pics as well. The firmware update appears to fix it. However, no release of the movie mode to the North American market yet. <grumble>
Other than the lacking movie mode (available in all other versions of this camera except in the North American market), I've been very pleased with the camera.
Casio Exilim EX-Z4 firmware update
Threaded Mode