After a 2 month wait, a fourth, and hopefully final beta of the phpBB2/phpNuke integration HOWTO is available. There were a few minor changes and bug fixes that had to be made, and the guide has been split into two parts:
Part One (click here): For those with new phpNuke and new phpBB2 installations.
Part Two (click here): For those with existing phpNuke installations (and the Forums module) who wish to integrate standalone phpBB2 into their site as a replacement.

Please read them, try them out, and post any results to the appropriate fora.

Thanks,
Dariush Molavi