The book by Kathy Sierra and Bert Bates (the SCJP Study Guide, also known as K&B) is available for SCJP 6, and also other SCJP study books are available for SCJP 6.
Have a look at the SCJP FAQ (see Treinmin Clark's link above). The SCJP FAQ contains a lot of useful information on preparing for SCJP, including a list of free and commercial mock exams.