This is not a tutorial but a description of what is technically possible to do. :-)

I have been lately thinking on how to open a very lightweight version of a forum using miniBB. The easiest way in my opinion would be to create a new theme specifically for mobile phone etc. The fun part is that several miniBB's can be installed and they all can use one specific database. So this means that there can be a normal version for standard Web browsers and a stripped version for cellphones, iPad's and so forth.

For example the main forum can be located in www.mydomain.com and mobile version could be put to subdomain www.mobile.mydomain.com. Or mobile version can as well have it's own domain, like www.mydomain.mobi. Both forums can be linked via setup_options.php to use same database. If database is being used from outside the primary forum's server, database can somewhat easily be accessed remotely if server's settings are done properly.

If someone is worried about duplicate content, it's very easy to deny access from robots and spiders by putting a password protection to mobile version's forum by putting inside setup_options.php these:

$protectWholeForum=1;
$protectWholeForumPwd='password';

Or if password protection doesn't feel right, some robots and spiders can be blocked using robots.txt and/or .htaccess.

You are closely to the true, but you just need to wait a little before we launch the official tutorial for that :) Actually I have teamed up with guys from baby.lv forums who were interested in mobile version, and currently, it's almost developed. Last testing is performed. You can see for yourself (be afraid of the Cyrillic text): m.baby.lv.

It is of course not about having two identical copies of the software. This is actually lame. You will kill yourself later on upgrades and routine work, if you have multiple copies. Actually, multiple copies solution is for those who want to install it once and forget about it. It's not practical.

The practical solution is to run both versions on the same core, and dynamically allow the script to use the alternative set of templates (located in [templates] folder) and CSS file (bb_mobile_style.css) depending on which domain is loaded. Mobile subdomain should point to the same folder as the root domain.

Duplicated content may be set defining $metaRobots var (NOINDEX,NOFOLLOW tags for all pages) or in robots.txt. The password protection will also work for regular visitors, it's not comfortable for them, to enter password for accessing the content, specially on mobile phones ;)

Hey, really I am very much excited to read about this mobile version of the forum. It would be really very interesting to have access to the forums on mobile itself. Then it would be very convenient. I am just looking forward to it. When can we expect it to be launched officially?

It is currently passing the final testing stage. I hope to the end of February we'll get something rolled.