This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
So, my guess is that you are safe using your HFSJ copy to prepare for SCWCD5... And by the way: the new exam for SCJP has undergone a similar "cosmetic" operation (with only Navigable and Console added to the objectives).
I actually wonder what the purpose of this second edition is, given the minor (and apparantly misleading) changes in the SCWCD 5 objectives, and the fact that the O'Reilly page gives exactly the same info as for the first edition! Only from the book's new cover, I can see that there is a new mock exam (why?).
I think O'Reilly would much better invest in an second edition of Head First EJB, since the EJB spec (EJB 3) in Java EE 5 has changed dramatically compared to J2EE 1.4, and has made the first edition seriously outdated (though still good for people working in a pre-Java EE 5 environment)! There is a genuine need out there for a new edition of this otherwise excellent exam prep book, and I can't see (other than maybe the author's lack of time) why O'Reilly has been waiting for so long to come up with one...