10 years is definitely too long. I would tell anyone preparing for the CPA exam to use nothing more than 1-2 years old so that they have all the current info. The profession of Accounting is always changing and the content of the exams will reflect this.
With that being said, review books older than a couple years will still contain useful information, they just won't be 100% up to date and I would not rely on them to pass the exam. People have to spend so much $ to take the exams why risk not passing because you didn't have the one piece of new info or you were using old information, standards, etc.
The exams are going to change significantly in 2011 as well, so I would definitely recommend new materials for 2011.
AUD - 85 (7/24/09) BEC - 90 (8/31/09) REG - 86 (11/16/09) FAR - 82 (05/11/10) *I'm a CPA!!!