What's The Deal With Timeline On Facebook Profiles?

Based on what we’ve seen from both Facebook friends and comments on our posts, the rollout of timeline on profiles appears to be occurring gradually, with no discernible pattern.

Facebook would only say:

We don’t have a time frame to share on when everyone will have timeline, but we’ll keep you posted.

Could Facebook be keeping the rollout slow in order to monitor how its users are adapting to timeline? Or is the social network waiting until after its initial public offering to make a decision one way or the other?

It would be a huge upset if the social network decided to abandon the upgrade to timeline for users, but the slow pace has aroused our curiosity, especially when compared with the haste with which timeline for pages was rolled out.