No, Facebook is not making an IPO (a public offer of its shares), they are making a lot of your information more visible to the outside of your friends circle. The new changes in privacy settings (vaguely labelled as new privacy settings) will make most of your data previously visible only to friends, available to the friends of your friends (which looks mild but is an exponential growth) and to the public (that is any of the half a billion Facebook users and even beyond that, as it should up in the public web profile.

Of course, you are invited to change these settings, but the way the page is phrased is very ambiguous. Picking "new setting" is hardly explicative, although as you hover over the corresponding radio button you'll see the permission you are granting. Clearly, Facebook wants to absorb Twitter. But most Facebook users tend to consider their post, pictures, shared videos "for their friends" and not for public consumption. This is a change taht will see a lot of resistance for sure.

Some more info on John Battelle blog at http://feedproxy.google.com/~r/JohnBattellesSearchblog/~3/wBGLwuvJQeY/005072.php and on the Facebook blog post explaining the change.