We've released Beyond Compare 4.0.3.

This version fixes a code signature failure on OS X 10.9 and 10.10, it also includes numerous bug fixes and polishes.

See the changelog for a full list of changes.

Users of OS X 10.8 or older:
Updating using Beyond Compare > Check for Updates hangs on OS X 10.8 or older. As a workaround, download the new version using a web browser and copy it to the Applications folder to update.