onloadRegister is not defined
tz_autoset is not defined
typeaheadpro is not defined
editStatus is not defined
I assumed they had made site code changes and messed things up, so I sent them an email to tell them :)
They replied and told me it was a caching issue (probably), which it wasn't as that didn't fix it.
I then noticed that Twitter also had the same (similar) errors.
Searching only found one one item, and that was a guy from UAE who complained that static.ak.facebook.com (which is used by Facebook) was censored in his country, hence the problem.
I investigated a bit more, and lo and behold, static.ak.facebook.com was actually in my Firefox Addblock's exclusion list. It was a fully qualified url, not a wildcard (as I am apt to add) so I'm not sure how it got there.
In error console it was there all the time (curse/love firebug):
Warning: Error in parsing value for property 'display'. Declaration dropped.
Source File: http://static.ak.facebook.com/css/common.css.pkg.php?c=19:12:60635
Anyway, once removed, everything worked fine.