About.com's Guide to Italy reports that as of March 9, 2008, it will cost you to visit the Roman Forum.
The current Colosseum and Palatine Hill combination ticket will also include admission to the Roman Forum and will now be valid for two days.Read Martha's article: Rome Forum No Longer Free.

Comments
What is the world coming too?
From my experience, one needs more time, i.e., being able to go back at will would be a nice idea.
(And a bad example . . .)