There was a portal project started long ago that was dropped. I believe they decided to wait until the next release (phpBB3 aka Olympus) was available before picking it up again.
No word on whether the intention is still there, but as we've been through (as I write this) 5 beta cycles for Olympus there is definitely progress being made on the core product. Once it's released (don't ask when that will be
) the idea might be revisited again.