iWeb 3.0.3 contains "bug fixes and improvements," and Apple specifically calls out the following changes:
* Addresses an issue when using the iSight Movie widget on certain Macs
* Addresses an issue publishing iWeb sites using FTP
* Improves compatibility with Mac OS X
The hefty update (185.9MB on my Mac Pro) is available now via or through OS X's Software Update mechanism (Apple doesn't sell iWeb on the App Store).