Hello Peter,
I asked the same question here a couple of days ago, no answer thoguh. I wanted to join the PHPBB and MediaWiki together with one login just as you. I found a quite ugly lite fix that did it though.
First I joined the together the usertables for phpbb and mediawiki. I used the one for phpbb as I already have all my users there, and merged in all the columns for mediawiki user-table.
Then I changed all the table and columns references in mediawiki to match phpbb usertable and username and password column.
Half way there. Users from phpbb can now log in with the same details in my wiki. New registrations will be directed to phpbb registration form. Luckily mediawiki and phpb encrypt passwords the same way.
Okay, that's all very neat! How do you generate the "missing bits" for mediawiki? I'm not sure I like the hacking the mysql DB though - for future compatibility that seems a bit... scary. I guess it would be possible using database triggers, but... those don't exist yet in MySQL.
Here comes the ugly part.
Users login to the wiki, mediawiki valides the password, if correct the information will be posted into the php-loginscript. Not good, not secure, not stable, but it works. A lot of things could go wrong there.. and I wouldn't recommend it.
Not sure I get this? What isn't secure about this? Do their passwords get posted or something? I guess I don't know -yet- how the wiki login works...
I though I should try and make something better, but I hanv't yet. So I made a fast easy hack.
Well, I for one would love to help you with this - or at least do something so I can use the same system. I mainly asked here because I didn't want to re-invent the wheel.
- bram