db4o 4.3 has been released as a "production" version today. This release includes all the changes in the development releases 4.1 and 4.2. The most important new feature stepping up from 4.0:
- Database file sizes of up to 254GB are possible

New features in 4.3:

• File IO is pluggable
  To create your own file IO implementation, you simply have to inherit from the abstract class com.db4o.io.IoAdapter and implement all the abstract methods. Here are some possible usecases why you may consider to write your own IoAdapter implementation:
  - achieve maximum performance with a native library for your platform
  - encrypt and decrypt slots with any fixed-length encryption mechanism of your choice
  - improve your security against hardware failures with a read-after-write check
  - mirror file IO to a redundant secondary or backup system
  
• The API documentation is now supplied as a Windows help file:
  /db4o-4.3/doc/api/db4o.chm
  

Enjoy!