Ok, I got the preview mode and the usergroups working.

to test the usergroups, login as UserNoPoll with password "password". the usergroup he belongs to is not allowed to post polls.

Mind you, the hack has gotten pretty complex.

11 new templates (most are just dupes of existing ones, with "post" changed to "poll")

1 new file (poll.php)

4 files need modification (editpost.php, options.php, showthread.php and usergoup.php)

2 New tables (poll and pollvote)

2 tables need to get an additional column

scared yet? I might provide the 4 files needing modification in various versions (1.1.2, 1.1.3, together with private msg hack) to simplify the hack.