I have been getting a lot of questions on how I enabled Facebook Timeline for my profile. I think people are over-complicating it a little. To enable it just head over here - Enable Facebook Timeline Now. It's literally as simple as that.
Facebook Timeline launched worldwide on the 15th December. At the moment you can choose to opt in for it, then when anyone visits your profile, they see it too. No word on when it will become default, or if it will ever become default.
The way it's looking though, it will most probably become default. People will inevitably hate it at first because many people hate change and hate adapting. After a few months, you'll realise it's the best thing Facebook has ever done.