Just got an update for xorg-server. When i saw the notification i thought 'should it be...', but no.
Would have been too good to be true, i guess.
When searching the internet you'll notice that many people are affected by this. Not all of them even understand that their problems mainly have got to do with the incompatibility with the xorg version that comes with 12.04. So plenty of bugreports are filed for. I think it's somewhat of a fault or imperfection that Ubuntu doesn't warn users for not being able to use the NVidia drivers (for the time being) by updating. Of course you can wait and see what others report, but if a version gets out of beta-status, it would prevent a lot of disapointment and problems to get such a warning. Particularly since the nouveau driver simply reduces functionality compared to the NVidia driver (lack of proper TV-out for instance).
Trying to add
Option "IgnoreABI" "True"
to xorg.conf won't work either, since the driver cannot even be installed. I guess for the moment the only possible 'solution' is probably indeed downgrading to the previous version of xorg like geribeto suggests, although many people advise against that.
Does anybody know if someone has already done that succesfully? Without 'breaking' other things, dependencies etc...?