As a result of your article in 172, I bought an Acer Iconia W500 tablet to play with.
I first installed OpenSuse 12.3, and found it wanting. I couldn't get a virtual keyboard on the login screen, and the system wouldn't sleep or hibernate properly. Other than that, lots of things worked great, but it was a dealbreaker.
So along the lines of your article, I started to install Ubuntu. But I normally use Mint KDE, so I said... what the heck?
Of course I still didn't have a virtual keyboard inside kdm, but at least I was in a more familiar environment. After diligent searches on the Net, I discovered no one had figured this out yet. So I set out to do it.
I just found an easy solution to this in Mint KDE 14.
edit /etc/kde4/kdm/kdmrc so that the line:
Then, edit /etc/kde4/kdm/Xsetup
insert the following command, PRIOR to the line which begins /sbin/initctl
That's it. You'll lose your Mint theme, and the login screen will instead say "Kubuntu". But you'll have a virtual keyboard onscreen.
By the way, I just posted this also to the Linux Mint Forums.