By popular demand, commenting is now enabled. Authentication happens via OpenID only; all comments will be moderated to combat spam. Moderation in ikiwiki seems to happen mainly via the web interface (I know about the RSS) so there may be a certain delay until I approve new comments.
If anyone happens to know how to make ikiwiki handle moderation gracefully within a git-based workflow, do leave a comment. That's possible, now :)
lindi: Yes, commenting is taking ages indeed. I will be migrating to a faster machine soon. That should fix things.
aatoponce: I considered this, but I think I will go with manual moderation, for now.