FB Javascript into URL

I have noticed an increasing number of Fan pages getting you to enter javascript into the URL before allowing access to the content. This seems to be replacing the old "Become a Fan" system.

I was wandering what that Javascript does?

Yes.. I have tried it and it does reveal the content... but... where's the CPA offer!!?

On step 3.

You see a link..

Or you can iframe your offer.
Nothing much more than that.