yeah there are some issues with the site.back at the thread about "mobile under 10K with GPS", my reported post was shown as first post...although it is corrected now...
So ico, do you think you can implement something. See there are couple of options. Tapatalk (although I hate its sluggishness), which does not make any change in the existing setup (except for addition of a single line) and uploading of a folder.
Second option (more feasible) is to have a mobile theme enabled which drastically reduces the bandwidth required to open the forum on mobiles. Here a couple of threads to go through.
A Very Lightweight Style for Small Screen Devices (cell phone/iphone/mobile/android) - vBulletin.org Forum
Mobile Style for vBulletin 4.0 - vBulletin.org Forum
I have a vBulletin license. I have implemented Tapatalk on my forum. Will try mobile themes too and let you know.